At that moment ,everybody began to laugh and sing .

问题描述:

At that moment ,everybody began to laugh and sing .
新概念第二册第九课的一句话.从began可以看出是一般过去时,为什么laugh和sing 不用过去式.

为你解答.
有一个固定用法 begin to do sth "do" 所以就要用动词原形的
求采纳 不懂追问