become用法说明
1. 用作连系动词，其后可接名词、形容词、过去分词等作表语：
He became a teacher at (the age of) 17. 他17岁就当了老师。
The weather became warmer. 天气变得暖和起来。
Soon the roombecame crowded. 不一会儿房里就挤满了人。
注意：其后接过去分词时，可表示被动或结果；但表示被动时，其后一般不接 by短语。比如不说：
Soon the room became crowded bystudents.
2. become 是终止性动词，因此要表示“成为…有多长时间”，英语不能将become与表示一段时间的词或短语连用：
他
正：He became a teacher ten years ago.
正：It’s ten years since he became a teacher.
正：He has been a teacher for ten years.
误：He has become a teacher for ten years.
3. become 之后一般不接不定式表示“逐渐…” (此时可用 come / begin＋不定式)：
正：He began [came] to like English. 他开始喜欢英语起来。
误：He became to like English.
正：He became ill yesterday. 他昨天病了。
误：He became to be ill yesterday.
4. 用于习语 become of, 表示“发生”、“遭遇”等 (常与 what连用)：
What has become of the girl? 这个女孩后来怎样了?
I don’t know what will become of me if I fail this time. 要是我这次不成功，我不知我会怎么样。