在大型吊装施工中，锚碇多采用（）。

A researcher is interested in testing to determine if the mean of population one is greater than the mean of population two. The null hypothesis is that there is no difference in the population means (i.e. the difference is zero). The alternative hypothesis is that there is a difference (i.e. the difference is not equal to zero). He randomly selects a sample of 9 items from population one resulting in a mean of 14.3 and a standard deviation of 3.4. He randomly selects a sample of 14 items from population two resulting in a mean of 11.8 and a standard deviation 2.9. He is using an alpha value of .10 to conduct this test. Assuming that the populations are normally distributed, the degrees of freedom for this problem are _______.

A、23

B、22

C、21

D、2

A、鲍照

B、谢灵运

C、江淹

D、庾信

A、均匀、各向同性

B、均匀、各向异性

C、不均匀、各向同性

D、不均匀、各向异性

A、

B、

C、

D、以上均不是

A、房室瓣关闭

B、房室瓣开放

C、动脉瓣开放

D、动脉瓣关闭

A、“贵古贱今”

B、“崇己抑人”

C、“信伪迷真”

D、“各执一隅之解”