—I hear a traffic accident happened yesterday. Was it terrible ?        

—Yes. A car _____ and all the people in it were badly hurt. But luckily, none of them was killed.      [ ]

A. fell over

B. fell behind

C. fell off

D. fell down to

圆锥角膜早期有效的诊断方法是（）。

A.裂隙灯检查

B.眼底检查

C.角膜地形图分析

D.角膜曲率检查

E.验光