被称为“十二经之海”的是（） A.带脉 B.督脉 C.阳维脉 D.阳跷脉 E.冲脉

Directions: Write an essay of 160-200 words based on the following drawing. In your essay, you should

1) describe the photos briefly,

2) explain its intended meaning, and

3) support your view with an example/examples.

You should write neatly on ANSWER SHEET 2.

There are fifty students in our class. Some are girls, ______ are boys.     [ ]

A. the other    

B. other    

C. others    

D. the others

）重量为G₁的均匀球夹在光滑竖直平面和45°倾角的光滑斜块之间，如图所示，斜块重G₂，斜块侧面与水平桌面间的摩擦系数为m₀，求：G₁的最小值为多大时，才能使斜块滑动。

防止锅炉炉膛爆炸事故发生的措施有哪些？

从基站接收端位置测试上行噪声电平，要求噪声电平平均（）。

A.小于-103dBm

B.小于-112dBm

C.小于-125dBm

D.小于-120dBm