1.What do you think _____an apple ______to the ground?
A.cause;to fall B.to cause;falling C.causing;falling D.causes;to fal
2.He looks very young.He ____be over 30
A.can't B.may not
3.With so much work _____my mind,I almost break down
A.filled B.filling C.being filled
4.He wrote a letter to me ____that his trip had been put off
A.informing B.informed Cinform
不仅给出答案 最好还有解释哦 谢谢