2017年高考英語備考點(diǎn)：begin(start) doing/to do句式

begin(start) doing/to do
    begin / start to do sth
    begin / start doing sth.
    1)　談及一項(xiàng)長期活動(dòng)或開始一種習(xí)慣時(shí)，使用doing.
    How old were you when you first started playing the piano?
    你幾歲時(shí)開始彈鋼琴?
    2)　begin， start用進(jìn)行時(shí)時(shí)，后面動(dòng)詞用不定式to do
    I was beginning to get angry.
    我開始生起氣來。
    3)　在attempt， intend， begin， start 后接know， understand， realize這類動(dòng)詞時(shí)，常用不定式to do.
    I begin to understand the truth.
    我開始明白真相。
    4)　物作主語時(shí)
    It began to melt.