一般来说,二者可以互换.但以下情况用 to do:
1. 主语不是指人,而是it等.如:It began to rain.
2. begin后接表示心理活动的词.如:begin to know
believe, wonder, think等.
3. begin本身是ing形式,为避免重复后接to do 即,beginning to do
另,
如果谈论一个长期的习惯动作开始养成时,更加常用begin doing.例如:
How old were you when you first began playing the piano?