用以测定平均性质的试样可以用（）。
A、等流样
B、排放样
C、间歇样
D、时间比例样
参考答案：B
When forbidden to surf the Internet, teenagers often _____ surfing it, saying that it provides them with colorful entertainments, a convenient means of communication as well as useful information
A．argue about
B．argue with
C．argue for
D．argue against
选择填入流程图2.2的合适的语句，它们都完成计算“1+2+3+4+5”的功能。
A．i＜5 B．i＞＝5 C．i＜＝5 D．i＞5
