常效避孕针避孕率可达()
A.96%~98%
B.98%
C.99%
D.99.7%
E.99.95%
参考答案:B
解析:
常效避孕针用法为每月注射1次,有效率达98%。
如图,BD平分∠ABC,DE∥BC,过E作BD的垂线交BD于O,交BC于F,P是ED的中点,若OP=5,则BF的长为( )。
— How did you like the lecture tonight?
— Very________.I doubt if I will come to this kind of lecture next time. [ ]
A. encouraging
B. encouraged
C. disappointing
D. disappointed