问题

Radium salts, which have been found to _____ in bones, give rise to cancers of the bone.

A:pile up
B:build up
C:keep up
D:pull up

正确答案是：

同类题型

Travelling from England toScotland you _______.

What’s Tom like —He’s _______ .He always gives the seat on the bus to someone.

I’m still wondering which school our son should choose. — him alone, he can make up his mind.

We were astonished __________the templestill in its original condition .

d he would arrive before seven,and______