Ⅱ. 单项选择(15分)
根据句子的意思，从所给的A、B、C三个选项中选择一个能够填入空白处的最佳选项。
( ) 17. _____ less than ten years, it develops from a seed _____ a full-grown tree.
A. In, into B. For, into C. At, to
( ) 18. He doesn’t live here any longer, he _______
A. moved away B. has moved away C. was moved
( ) 19. When I met him last week, it was the first time we had seen each other _____ we were at school.
A. for B. from C. since
