（），即甲基苯丙胺，外观为纯白或黄色结晶体，晶莹剔透。
A.可卡因
B.冰毒
C.海洛因
D.吗啡
参考答案：B
— What's your plan for the summer holiday ?
— I'v no idea, but I'v decided at home and have a good rest first. [ ]
A. stay
B. to stay
C. stayed
D. staying
构成“传染过程”必须具备的因素是
A．病原体、易感机体B．寄生虫、中间宿主及终末宿主C．病人、污染物、易感者D．传染源、传播途径、易感人群E．微生物、媒介及宿主
