It is very difficult for a person to know how fast a car is trave_英语解答

It is very difficult for a person to know how fast a car is traveling为什么是is travelling,原因!

人气：222 ℃　时间：2019-12-06 02:36:34

解答

is traveling 是现在进行时
现在进行时的动词形式是：
be(am,is ,are) + 现在分词
由于主语是三人称单数,所以用 is traveling