相须、相使配伍可产生的作用是（）
A.协同作用，增进疗效
B.拮抗作用，降低疗效
C.减毒作用
D.产生毒副作用
E.增加毒性
参考答案：A
—Where is ________ pen pal from?
—He is from Australia．[ ]
A. you
B. yours
C. your
D. he
— Why was Professor Liu thundering in the classroom yesterday?
— A student's interrupting his speech ________ the burst of his anger.[ ]
A. set up
B. set out
C. set about
D. set off
