进行疫苗预防效果评价宜采用
A．简单随机抽样B．系统抽样C．整群抽样D．分层抽样E．多级抽样
参考答案：E
Even students with intelligence can be excellent students after improving their study habits.
A．average
B．unusual
C．splendid
D．popular
按时间顺序排列下列历史事件
①遵义会议②蒋介石发动第五次“围剿”③中央红军被迫开始长征
④三大红军主力胜利大会师⑤中央红军到达陕甘革命根据地[ ]
A．①②③④⑤
B．②①④③⑤
C．②③⑤④①
D．②③①⑤④
