start,begin,continue,cease这样一些表示开始,继续和结束意义的动词,既可以接to do ,也可以接V-doing,大体上说,意义没有明显的差别.但在某些有限的情况下,start to do sth 意思是指“开始去做某事”,有“潜在的可能”；start doing sth 意思是指“开始做某事”,有“实际进行”的意思.当涉及到多次活动时使用start doing更为恰当.
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.