___the people have become masters of their own country that science can really serve the people
问题描述：
___the people have become masters of their own country that science can really serve the people
A only when B it is only when C only when D it is only when
答
b跟d不是一样吗b应该是then选d原因肯定不能选only开头的，因为句子不是到装句那then后面不能接从句