特种作业操作证每( )年复审1次。
A．2 B．3C．4 D．5
参考答案：B
A few days after the interview, I received a letter _____ me admission to the university. [ ]
A. having offered
B. offered
C. to be offered
D. offering
下列疾病中属于遗传病的是（ ）
A．艾滋病
B．流感行性感冒
C．乙型肝炎
D．血友病
