When he suddenly ________ up the subject of genetic engineering, there was an embarrassedsilence.
西汉时，主张文治，反对 "马上治天下 "的是 ()
1953 年，为解决粮食供应紧张问题，我国采取的新措施是 ()
He asked me whether my brother ________ (fly) to Beijing.
我国对资本主义工商业实行和平赎买有利于___________。
