人们登山有好多理由。有些人是为了享受攀高的挑战，其他人则是为了探索和崇尚大自然的美(景)。

Sentence No. 1 Evidence shows that older people who participate in lifelong learning are healthier, more active and have more social contacts.

Sentence No. 5 People climb mountains for many reasons. Some enjoy the challenge of trying to reach high places. Others like to explore and admire the beauty of nature.