Question

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

 

Answer 1

B

build up(=accumulate) 积累；pile up 堆积；keep up 保持，维持；pull up 停车。