下列不属于机械性吞咽困难的是（）。
A.咽喉结核
B.甲亢性肌病
C.食管癌
D.纵隔占位病变
E.主动脉瘤
参考答案：B
骨瘤好发部位是（）
A.长骨
B.短骨
C.椎骨
D.颅面骨
E.髂骨
My mother passed the driving-test at her first attempt. It was all ______ she had been practicing so hard.
A. why
B. because
C. that
D. what
