become的两点用法说明
1. 用作连系动词，其后可接名词、形容词、过去分词等作表语。如：
They became great friends. 他们成了莫逆之交。
He soon became angry. 他过了一会儿就生气了。
At last the truth became known to us. 我们终于知道了真相。
2. 其后一般不接不定式。如：
他开始对生物感兴趣了。
误：He became to be interested in biology.
正：He became interested in biology.
于是我们开始喜欢他了。
误：Then we became to like him.
正：Then we began [came] to like him.
