兰科(Orchidaceae)植物花因子房呈180°扭转，使唇瓣位于上方。( )

A．To make coins lighter.B．To conserve silver.C．To use up surplus copper.D．To make coins last longer. 点击查看答案

It was not until she had finished all her work（）.

A.did she return
B.that she returned
C.when she returned
D.that did she return

点击查看答案&解析