He invented this bicycle _____1839.
A：on
B：with
C：in
- There ________ many trees at the foot of the mountain.
- But now they are slowly disappearing because of human activities.
请以“我们一起走过”为题写一篇作文。
要求：①内容具体，有真情实感；②文体不限（诗歌，戏剧除外）；③不少于600字；④文中不得出现真实的人名、校名、地名。
