It is said that Bob will drop out of school because his family cannot afford the school fee. – _____, let’s give him a hand.

She didn’t mention her troubles to Mr. Li，who might have helped her ______.

She is too fat, but she can’t ________ sweets.

I’ve known Sarah for nearly ten years．She __________ once my customer．

_____to nuclear radiation, even for a short time , may produce variants(变异体) of genes in human bodies.