____ at the door before entering,pleaseA.knocked B.To knockC.KnockingD.Knockchoose?why?祈使句就能说明选D？
问题描述：
____ at the door before entering,please
A.knocked
B.To knock
C.Knocking
D.Knock
choose?why?
祈使句就能说明选D？
答
D Please knock at the door before entering.
答
D
答
c
动名词做主语
答
D.Knock
因为是祈使句
（祈使句就是要用动词原型的，没错）
答
D 祈使句 命令式 动词需要用原形 就是knock啦