（）can help us to keep healthy.ADoing activities B（）can help us to keep healthy.ADoing activitiesBDo activitiesCDoes activityDDo activity
问题描述：
（）can help us to keep healthy.ADoing activities B
（）can help us to keep healthy.
ADoing activities
BDo activities
CDoes activity
DDo activity
答
() can help us to keep healthy.
A. Doing activities
B. Do activities
C. Does activity
D. Do activity
纯从语法上讲，100%用A，但英语为母语的人不会说：Doing activities can help us to keep healthy。他们会说：Doing exercise can keep us fit. 或者别的说法，但肯定不会说 Do activities can help us to keep healthy.
答
ADoing activities
动词的ing形式才可以做句子主语