当你给朋友打电话时，相当于"喂"的打招呼用语是________。[ ]
A. Hello
B. OK
C. Good morning
D. Fine
答案：A
I told my mother I wasn't worried about my exam. But in fact I ___________. [ ]
A. did
B. was
C. have
D. had
催化剂中毒分哪几种？分别叙述。
