机电行业的苯及其衍生物等有机蒸汽净化方法是( )。
A．袋滤法
B．洗涤法
C．燃烧法
D．开口罩
参考答案：B
12. Your friend acts ______ he were a trustworthy person but as a matter of fact he seldom keeps_____. So remember not to trust him with anything important.
A. as if; his words B. as though; his word
B. even if; his promise D. even though; his promises
训诂学是一门什么样的学科？
