So suddenly      that the animals in the zoo looked very frightened during the total solar eclipse.

A．did the sky turn dark

B．the sky did turn dark

C．turned the sky dark

D．was the sky turned dark

患者男性，30岁，上颌双侧中切牙缺失，可摘局部义齿修复，双侧第一前磨牙做基牙，一般情况下腭侧基托应设计至

A．尖牙远中

B．第二磨牙远中

C．第一磨牙远中

D．第一前磨牙远中

E．第二前磨牙远中