题目内容：

I with my sister _____(play)badminton in the yard now.空上填什么?

优质解答

am playing
with是介词,with my sister是介宾短语作定语,修饰I.句子的主语是I.now说明这个句子是现在进行时.所以谓语动词填am playing.
如果with换成连词and,说成My sister and I,则主语是复数,谓语动词填are playing.