下列植物的变态叶分别属于：玉米苞叶，百合鳞叶，豌豆（），仙人掌托叶刺。
A、鳞叶
B、苞叶
C、叶卷须
D、托叶刺
参考答案：C
患者右上第一磨牙咬合痛。X线片示根尖周暗影，提示根尖周吸收破坏的牙槽骨有
A．硬骨板，松质骨
B．密质骨，硬骨板
C．骨髓，骨小梁
D．密质骨，松质骨
E．骨小梁，密质骨
– Do you know _____ this time yesterday?
-- Sorry, I don’t know.
A. what she is doing B. what was she doing C. what she was doing
