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【单选题】
一般人们把声音频率超过()的声波称为超声波A.
10kHz
B.
20kHz
C.
10MHz
D.
20MHz
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反馈参考答案：
举一反三
【简答题】请说出联想电脑的广告口号
【单选题】_____ she is the only daughter of the boss, she started from the lowest position as a common employee.
A.
Unless
B.
While
C.
Since
D.
As
【单选题】Had she started to do it right now, she will get it done before Christmas Eve.
A.
Only she starts
B.
If she starts
C.
If she had started
D.
Would she start
【判断题】ADF检验是通过三个模型来完成,首先从含有截距和趋势项的模型开始,再检验只含截距项的模型,最后检验二者都不含的模型。通常认为,只有三个模型的检验结果都不能拒绝原假设时,才认为时间序列是平稳的,而只要其中有一个模型的检验结果拒绝了零假设,就可认为时间序列是不平稳的。
A.
正确
B.
错误
【单选题】She might have been in time for the train, but she _______late.
A.
started
B.
has started
C.
was to start
D.
had started
【单选题】现需制造一汽车传动齿轮,要求表面具有高的硬度、耐磨性和高的接触疲劳极限,心部具有良好的韧性,最好是采用下面哪种材料及工艺?( )
A.
T10钢淬火+低温回火
B.
45钢经调质处理
C.
20CrMnTi经渗碳后淬火+低温回火
D.
20钢经表面淬火
【单选题】The mother tried to look calm at the sad news, but the moment she started to speak, she ______ .
A.
displayed herself
B.
delayed herself
C.
betrayed herself
D.
strayed herself
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