语法学习技巧|begin(start) doing/to do

begin / start to do sth
begin / start doing sth.
1)说到一项长期活动或开始一种习惯时，用doing.
How old were you when you first started playing the piano?
你多大岁数时开始弹钢琴？
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这种动词时，常用不定式to do。
I begin to understand the truth。
我开始了解真相。
4)物作主语时
It began to melt1.