1He has a friend who____ the piano very well.这种句型里的单词要加s还是原型?

题目

1He has a friend who____ the piano very well.这种句型里的单词要加s还是原型?
2 I didn't know________.
A where does he live B where did he live
C where he lives D where he lived
这种句型的问句是怎么判断的?
3 Where_________live before you came here?
A did you used to B did you use to
C ues he to D he used to
这题为什么选B不选A呢?
第一题如果只有第三人称单数要不要加s呢？

答案

应该是plays,因为前面a friend是单数所以定语从句谓语也是用单数,就是第三人称单数才加s的呀D,首先这个是宾语从句,从句要用陈述语序,所以排除A,B,而且前面主句是过去式,所以从句要和主句一致也用过去时,所以选D这个...