______ watch do you want, this one or that one? [ ]
A. How
B. Who
C. Where
D. Which
答案:D
桔梗的功效是()
A.宣肺利咽
B.化痰利水
C.祛痰排脓
D.降气止呕
E.清热润喉
单项式-2xy2的系数是____________________________