一个圆柱体的底面半径与一个圆锥体的底面半径之比为4：1，该圆锥体的底面积为12.

脂蛋白密度由低到高排列的正确顺序是（）

A.VLDL、LDL、CM、HDL

B.HDL、VLDL、LDL、CM

C.LDL、HDL、VLDL、CM

D.CM、VLDL、LDL、HDL

E.CM、LDL、VLDL、HDL

根据合同法律制度的规定，下列各项中，属于无效合同的有( )。

A．恶意串通损害国家利益的合同

B．损害社会公共利益的合同

C．显失公平的合同

D．以合法形式掩盖非法目的的合同

阅读理解

     This year, Chongqing primary schools decide to start morning classes an hour later. This will help

students feel less tired. And most primary schools will begin the first classes at about9o'clock in the

morning.

     The students are happy about the change.

     Liu Ming told us that his class were excited by the news on the first day of the school. "Great! From

now on we students at Hope Primary School don't have to get up so early!" Liu said that he used to get

up at 6:40 am. Now he can get up at 7:50 am because class doesn't start until 8:50 am.

     Wu Hong feels the same. She said the new timetable(时间表) was good for her health. "I used to get

up at 6:30 am. I had to drink coffee every night, or I would feel too sleepy to finish my homework," said Wu. "Now I can finish it without coffee. Because I can sleep a little longer."

     Many teachers say the change will help students learn better. "Students used to doze(瞌睡) for the

first two classes in the morning," said Huang Shan, an English teacher at No. 1 Primary School. "But now

they are active and learn much better than before."

     But some parents are worried that more sleep will mean less learning. There used to be five classes in

the morning. Now there are only four.

      In fact, every coin has two sides. So does the change in the school timetable.

1 This year, most Chongqing primary schools started the first class at about ________.

A. 8:30 am      

B. 6:40 am    

C. 7:50 am      

D. 9:00 am

2. Hearing the news, the students at Hope Primary School felt _______.

A. worried      

B. sad          

C. excited      

D. angry

3. How many classes are there in the morning in Chongqing primary schools now?

A. Five.        

B. Four.        

C. Three.        

D. Two.

4. Which is RIGHT according to the text?

A. The students in No. 1 Primary School used to doze for the first two classes in the morning.

B. All the parents say the change will help students learn better.

C. The students will have to get up one hour earlier than before.

D. Many teachers are worried that more sleep will mean less learning.

操作系统是计算机系统中的一个（），它管理和控制计算机系统中的（）。

滑坡地段开挖作业，应从滑坡体两侧向中部自下而上进行。严禁拉槽开挖，弃土不能堆放在主滑区内。（）