Question

—Susan stays alone in the classroom and looks sad.
—_____________to her?

1. A.
   What happens
2. B.
   What has happened
3. C.
   What is happening
4. D.
   What was happening

Answer 1

B
B “某人發(fā)生了某事”即sth. happen to sb.，happen一般不用于進(jìn)行時(shí)；Susan不高興，說(shuō)明是（已經(jīng)）發(fā)生了某事，故用完成時(shí)，且完成時(shí)表示不高興的原因。