—What happened to Tom?

—He ______ his leg while playing football with his classmates.

A．had broken

B．has broken

C．broke

D．was breaking

植物适应强风的形态结构是( )。

A．树皮厚、叶小而坚硬等减少水分蒸腾的旱生结构

B．根系浅、材质脆软、树冠大

C．花一般都不鲜艳，但花的数目很多，常成葇荑花序或非常松散的圆锥花序

D．向背风方向弯曲，树冠向背风方向倾斜