五十而知天命是什么意思

百度 城市学是随着城市的发展，城市问题日益增加，研究和解决城市问题日益为城市发展所必须而产生和发展的。

Children have lunch in Liuzhuang Village of Pizhou City, east China's Jiangsu Province, Aug. 16, 2022. Liu Long, 35, is a Chinese martial arts enthusiast. He found that his three children were also interested in martial arts and often imitated the action of him when he was practicing, so he began to take the three children to do martial arts training. Local villagers also sent their children to learn martial arts from Liu.

As more and more children came to learn martial arts, Liu and his wife Gu Dandan founded a martial arts training class. Liu hoped that the children could grow up healthily and happily, and that martial arts could become their lifelong hobby. (Xinhua/Ji Chunpeng)

Liu Long's daughters Liu Yiting, Liu Yidian (up) and son Liu Yixing (C) have a break during training in Liuzhuang Village of Pizhou City, east China's Jiangsu Province, Aug. 16, 2022. Liu Long, 35, is a Chinese martial arts enthusiast. He found that his three children were also interested in martial arts and often imitated the action of him when he was practicing, so he began to take the three children to do martial arts training. Local villagers also sent their children to learn martial arts from Liu.

As more and more children came to learn martial arts, Liu and his wife Gu Dandan founded a martial arts training class. Liu hoped that the children could grow up healthily and happily, and that martial arts could become their lifelong hobby. (Xinhua/Ji Chunpeng)

Liu Long's daughter Liu Yidian performs Chinese martial arts in Liuzhuang Village of Pizhou City, east China's Jiangsu Province, Aug. 16, 2022. Liu Long, 35, is a Chinese martial arts enthusiast. He found that his three children were also interested in martial arts and often imitated the action of him when he was practicing, so he began to take the three children to do martial arts training. Local villagers also sent their children to learn martial arts from Liu.

As more and more children came to learn martial arts, Liu and his wife Gu Dandan founded a martial arts training class. Liu hoped that the children could grow up healthily and happily, and that martial arts could become their lifelong hobby. (Xinhua/Ji Chunpeng)

Liu Long (R) instructs his daughter Liu Yidian to practise Chinese martial arts in Liuzhuang Village of Pizhou City, east China's Jiangsu Province, Aug. 16, 2022. Liu Long, 35, is a Chinese martial arts enthusiast. He found that his three children were also interested in martial arts and often imitated the action of him when he was practicing, so he began to take the three children to do martial arts training. Local villagers also sent their children to learn martial arts from Liu.

As more and more children came to learn martial arts, Liu and his wife Gu Dandan founded a martial arts training class. Liu hoped that the children could grow up healthily and happily, and that martial arts could become their lifelong hobby. (Xinhua/Li Bo)

Liu Long and his children practice squat in Liuzhuang Village of Pizhou City, east China's Jiangsu Province, Aug. 16, 2022. Liu Long, 35, is a Chinese martial arts enthusiast. He found that his three children were also interested in martial arts and often imitated the action of him when he was practicing, so he began to take the three children to do martial arts training. Local villagers also sent their children to learn martial arts from Liu.

As more and more children came to learn martial arts, Liu and his wife Gu Dandan founded a martial arts training class. Liu hoped that the children could grow up healthily and happily, and that martial arts could become their lifelong hobby. (Xinhua/Li Bo)

Aerial photo taken on Aug. 16, 2022 shows Liu Long teaching children Chinese martial arts in Liuzhuang Village of Pizhou City, east China's Jiangsu Province. Liu Long, 35, is a Chinese martial arts enthusiast. He found that his three children were also interested in martial arts and often imitated the action of him when he was practicing, so he began to take the three children to do martial arts training. Local villagers also sent their children to learn martial arts from Liu.

As more and more children came to learn martial arts, Liu and his wife Gu Dandan founded a martial arts training class. Liu hoped that the children could grow up healthily and happily, and that martial arts could become their lifelong hobby. (Xinhua/Li Bo)

Liu Long leads the children on a run along a road for training in Liuzhuang Village of Pizhou City, east China's Jiangsu Province, Aug. 16, 2022. Liu Long, 35, is a Chinese martial arts enthusiast. He found that his three children were also interested in martial arts and often imitated the action of him when he was practicing, so he began to take the three children to do martial arts training. Local villagers also sent their children to learn martial arts from Liu.

As more and more children came to learn martial arts, Liu and his wife Gu Dandan founded a martial arts training class. Liu hoped that the children could grow up healthily and happily, and that martial arts could become their lifelong hobby. (Xinhua/Li Bo)

Liu Long teaches children Chinese martial arts in Liuzhuang Village of Pizhou City, east China's Jiangsu Province, Aug. 16, 2022. Liu Long, 35, is a Chinese martial arts enthusiast. He found that his three children were also interested in martial arts and often imitated the action of him when he was practicing, so he began to take the three children to do martial arts training. Local villagers also sent their children to learn martial arts from Liu.

As more and more children came to learn martial arts, Liu and his wife Gu Dandan founded a martial arts training class. Liu hoped that the children could grow up healthily and happily, and that martial arts could become their lifelong hobby. (Xinhua/Ji Chunpeng)

Liu Long takes children for warm up training in Liuzhuang Village of Pizhou City, east China's Jiangsu Province, Aug. 16, 2022. Liu Long, 35, is a Chinese martial arts enthusiast. He found that his three children were also interested in martial arts and often imitated the action of him when he was practicing, so he began to take the three children to do martial arts training. Local villagers also sent their children to learn martial arts from Liu.

As more and more children came to learn martial arts, Liu and his wife Gu Dandan founded a martial arts training class. Liu hoped that the children could grow up healthily and happily, and that martial arts could become their lifelong hobby. (Xinhua/Ji Chunpeng)

Aerial photo taken on Aug. 16, 2022 shows Liu Long practicing squat with his children in Liuzhuang Village of Pizhou City, east China's Jiangsu Province. Liu Long, 35, is a Chinese martial arts enthusiast. He found that his three children were also interested in martial arts and often imitated the action of him when he was practicing, so he began to take the three children to do martial arts training. Local villagers also sent their children to learn martial arts from Liu.

As more and more children came to learn martial arts, Liu and his wife Gu Dandan founded a martial arts training class. Liu hoped that the children could grow up healthily and happily, and that martial arts could become their lifelong hobby. (Xinhua/Ji Chunpeng)

Liu Long instructs his son Liu Yixing during training in Liuzhuang Village of Pizhou City, east China's Jiangsu Province, Aug. 16, 2022. Liu Long, 35, is a Chinese martial arts enthusiast. He found that his three children were also interested in martial arts and often imitated the action of him when he was practicing, so he began to take the three children to do martial arts training. Local villagers also sent their children to learn martial arts from Liu.

As more and more children came to learn martial arts, Liu and his wife Gu Dandan founded a martial arts training class. Liu hoped that the children could grow up healthily and happily, and that martial arts could become their lifelong hobby. (Xinhua/Li Bo)

Children warm up before Chinese martial arts training in Liuzhuang Village of Pizhou City, east China's Jiangsu Province, Aug. 16, 2022. Liu Long, 35, is a Chinese martial arts enthusiast. He found that his three children were also interested in martial arts and often imitated the action of him when he was practicing, so he began to take the three children to do martial arts training. Local villagers also sent their children to learn martial arts from Liu.

As more and more children came to learn martial arts, Liu and his wife Gu Dandan founded a martial arts training class. Liu hoped that the children could grow up healthily and happily, and that martial arts could become their lifelong hobby. (Xinhua/Ji Chunpeng)

Liu Long (R) and his wife Gu Dandan cook lunch for children in Liuzhuang Village of Pizhou City, east China's Jiangsu Province, Aug. 16, 2022. Liu Long, 35, is a Chinese martial arts enthusiast. He found that his three children were also interested in martial arts and often imitated the action of him when he was practicing, so he began to take the three children to do martial arts training. Local villagers also sent their children to learn martial arts from Liu.

As more and more children came to learn martial arts, Liu and his wife Gu Dandan founded a martial arts training class. Liu hoped that the children could grow up healthily and happily, and that martial arts could become their lifelong hobby. (Xinhua/Ji Chunpeng)

Liu Yiting, the eldest daughter of Liu Long, participates in obstacle training in Liuzhuang Village of Pizhou City, east China's Jiangsu Province, Aug. 16, 2022. Liu Long, 35, is a Chinese martial arts enthusiast. He found that his three children were also interested in martial arts and often imitated the action of him when he was practicing, so he began to take the three children to do martial arts training. Local villagers also sent their children to learn martial arts from Liu.

As more and more children came to learn martial arts, Liu and his wife Gu Dandan founded a martial arts training class. Liu hoped that the children could grow up healthily and happily, and that martial arts could become their lifelong hobby. (Xinhua/Ji Chunpeng)