我国职业病名单中，列入职业肿瘤，可引起间皮瘤的毒物是（）
A．联苯胺
B．氯甲醚
C．石棉
D．砷
E．焦炉逸散物
参考答案：C
_______ many times, he finally understood it.
A．Told
B．Telling
C．Having told
D．Having been told
Like some of my classmates, I can't live up to my teachers' expectations,___ , I let them down. [ ]
A. in other words
B. after all
C. what's more
D. more or less
