关于侵蚀性葡萄胎的诊断,下列哪项是正确的
A.光镜下见不到绒毛膜结构B.葡萄胎排出后不足半年内发病C.不发生脑转移D.能查到卵巢囊肿者E.血hCG异常升高
参考答案:B
Not until he retired from teaching three years ago ________ having a holiday abroad.
A.he had considered
B.had he considered
C.he considered
D.did he consider
中央电视台《实话实说》曾经播出过这么一幕,反伪科学斗士司马南,手拿铁锤,向头顶七八块青砖的主持人崔永元使劲砸去,青砖碎了,而崔永元却安然无恙,是崔永元有气功吗?还是……请你用动量守恒定律来分析这其中的道理.