债券的持有期收益率一定比票面利率大。
参考答案：错
He has been late three times_____the morning of last Friday. [ ]
A. in
B. on
C. since
D. Until
掘进巷道碹体砌反拱是因为（）严重。
A.顶板冒落
B.片帮
C.底鼓
