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?