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M: Yes. Nice to meet you, too, Ms. Pacher. W: Mr. Zhang will see you in a minute. Please take a seat first. Mr. Lee, would you like something to drink? M: Yes, thank you. W: Tea or coffee? M: Coffee, please, with milk and sugar. W: OK. It’ll be ready in a moment. (Five minutes later, the telephone rings. Susan answers the phone and turns to Mr. Lee.) W: Mr. Lee, Mr. Zhang is expecting you in his office. M: Good. Would you please tell me his room number? W: Sure, it’s Room 305. Let me show you there. M: Thank you.
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【单选题】某工作在放大状态的三极管，当基极电流IB由60μA降低到40μA时，集电极电流IC由2.3mA降低到1.5mA，则此三极管的动态电流放大系数β为（ ）。
A.
37.5
B.
38.3
C.
40
D.
57.5
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【单选题】In a hypothesis test comparing two population means, we use the z distribution when:
A.
the two population standard deviations are equal.
B.
both populations have at least 4000 observations.
C.
both population standard deviations are known.
D.
nπ and n(1-π) are both greater than 5.
查看完整题目与答案
【单选题】In a hypothesis test comparing two population means, the "=" sign always appears in the ( )
A.
null hypothesis.
B.
alternative hypothesis.
C.
upper tail of one-tailed hypothesis testing.
D.
lower tail of one-tailed hypothesis testing.
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【判断题】带传动的传动比准确。 2 、 V 带较平带传动能力大。 3 、同步齿形带是依靠带和带轮之间的摩擦力来传递运动和动力的。 4 、在一组使用中的 V 带中,若坏了一根,必须成组更换。 5 、 V 带传动时,两轮的转向相同。 6 、考虑 V 带弯曲时横截面的变形,带轮的槽角应小于 V 带横截面的楔角。 7 、 V 带的横截面形状是 V 形。
A.
正确
B.
错误
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【判断题】外在的情绪表现通常称之为表情。()
A.
正确
B.
错误
查看完整题目与答案
【单选题】In a hypothesis test comparing two population means, the "=" sign always appears in the:
A.
null hypothesis.
B.
alternate hypothesis.
C.
upper tail of the test statistic.
D.
lower tail of the test statistic.
查看完整题目与答案
【多选题】法洛四联征在胸部后前位片上的X线表现为( )
A.
心脏无明显增大
B.
肺门缩小，肺血管纤细
C.
心尖圆钝、上翘、心腰凹陷
D.
肺血少者可能见到侧支循环
E.
伴有右位主动脉弓则主动脉结在右侧
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【单选题】In a hypothesis test comparing two means of the independent normal populations, we use the z distribution test statistic when ( )
A.
both population standard deviations are known.
B.
the two population standard deviations are unkown.
C.
the two population standard deviations are equal.
D.
Both B and C
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【单选题】某工作在放大状态的三极管,当基级电流IB由60μA降低到40μA时,集电极电流IC由2.3mA降低到1.5mA,则此三极管的动态电流放大系数β为( )。
A.
37.5
B.
38.3
C.
40
D.
57.5
查看完整题目与答案
【单选题】Which of the following statements is NOT true about the level of significance in a hypothesis test?
A.
The larger the level of significance, the more likely you are to reject the null hypothesis.
B.
The level of significance is the maximum risk we are willing to accept in making a Type I error.
C.
The significance level is also called the level.
D.
The significance level is another name for Type II error.
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相关题目：
【单选题】某工作在放大状态的三极管，当基极电流IB由60μA降低到40μA时，集电极电流IC由2.3mA降低到1.5mA，则此三极管的动态电流放大系数β为（ ）。
A.
37.5
B.
38.3
C.
40
D.
57.5
查看完整题目与答案
【单选题】In a hypothesis test comparing two population means, we use the z distribution when:
A.
the two population standard deviations are equal.
B.
both populations have at least 4000 observations.
C.
both population standard deviations are known.
D.
nπ and n(1-π) are both greater than 5.
查看完整题目与答案
【单选题】In a hypothesis test comparing two population means, the "=" sign always appears in the ( )
A.
null hypothesis.
B.
alternative hypothesis.
C.
upper tail of one-tailed hypothesis testing.
D.
lower tail of one-tailed hypothesis testing.
查看完整题目与答案
【判断题】带传动的传动比准确。 2 、 V 带较平带传动能力大。 3 、同步齿形带是依靠带和带轮之间的摩擦力来传递运动和动力的。 4 、在一组使用中的 V 带中,若坏了一根,必须成组更换。 5 、 V 带传动时,两轮的转向相同。 6 、考虑 V 带弯曲时横截面的变形,带轮的槽角应小于 V 带横截面的楔角。 7 、 V 带的横截面形状是 V 形。
A.
正确
B.
错误
查看完整题目与答案
【判断题】外在的情绪表现通常称之为表情。()
A.
正确
B.
错误
查看完整题目与答案
【单选题】In a hypothesis test comparing two population means, the "=" sign always appears in the:
A.
null hypothesis.
B.
alternate hypothesis.
C.
upper tail of the test statistic.
D.
lower tail of the test statistic.
查看完整题目与答案
【多选题】法洛四联征在胸部后前位片上的X线表现为( )
A.
心脏无明显增大
B.
肺门缩小，肺血管纤细
C.
心尖圆钝、上翘、心腰凹陷
D.
肺血少者可能见到侧支循环
E.
伴有右位主动脉弓则主动脉结在右侧
查看完整题目与答案
【单选题】In a hypothesis test comparing two means of the independent normal populations, we use the z distribution test statistic when ( )
A.
both population standard deviations are known.
B.
the two population standard deviations are unkown.
C.
the two population standard deviations are equal.
D.
Both B and C
查看完整题目与答案
【单选题】某工作在放大状态的三极管,当基级电流IB由60μA降低到40μA时,集电极电流IC由2.3mA降低到1.5mA,则此三极管的动态电流放大系数β为( )。
A.
37.5
B.
38.3
C.
40
D.
57.5
查看完整题目与答案
【单选题】Which of the following statements is NOT true about the level of significance in a hypothesis test?
A.
The larger the level of significance, the more likely you are to reject the null hypothesis.
B.
The level of significance is the maximum risk we are willing to accept in making a Type I error.
C.
The significance level is also called the level.
D.
The significance level is another name for Type II error.
查看完整题目与答案
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