在常用的几种抽样方法中,最便于组织,并且节省经费的是()
A.单纯随机抽样
B.分层抽样
C.整群抽样
D.机械抽样
E.单纯随机抽样和机械抽样
参考答案:C
I have made great progress ________ his help. Which of the following is not correct?
A.with
B.because of
C.as a result of
D.because
当TA7343的压控振荡器停振时,故障现象是()。
A.无输出
B.输出立体声信号
C.只能输出单声道信号
D.A、B、C都有可能