1. 用作连系动词，其后可接名词、形容词、过去分词等作表语：

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。

He became a teacher at (the age of) 17. 他17岁就当了老师。

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：

他成为老师有十年了。

正：He has been a teacher for ten years.

正：He became a teacher ten years ago.

正：It’s ten years since he became a teacher.

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 became ill yesterday. 他昨天病了。

误：He became to be ill yesterday.

正：He began [came] to like English. 他开始喜欢英语起来。

误：He became to like English.

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。