问题

Radium salts，which have been found to ______ in bones，give rise to bone cancer.

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

正确答案是：

同类题型

It can be ______ to swim in a strange place.—I think so. We should swim with our parents or in a swimming poo1.

Rose is a very humorous girl, and she often ________ us with funny stories and jokes.[ ]

Ever since MaYun founded Taobao Website, the number of people shopping online ___quickly.

Volunteering is becoming popular in China — Yeah, people are now aware that helping others is helping themselves

mmer Palace is really beautiful In fact, Idoubt whether China has _________ park