继续讲解动词+doing 和 to do 的用法今天讲的是 begin 和 start 开始begin(start) doing/to do begin / start to do sth begin / start doing sth
1) 谈及一项长期活动或开始一种习惯时，使用 doing
How old were you when you first started playing the piano
你几岁时开始弹钢琴
2) begin, start 用进行时时，后面动词用不定式 to do I was beginning to get angry
我开始生 起气来
3) 在 attempt, intend, begin, start 后接 know, understand, realize 这类动词时，常用不定式 to do
I begin to understand the truth
我开始明白真相
4) 物作主语时 It began to melt
