已知A是乙烯，B、C、D、E均为常见的有机物，在一定条件下，它们有如下图所示的转

在做“绿叶中色素的提取和分离”实验时，研磨绿叶不需要加入[ ]

A．乙醇

B．碳酸钙

C．二氧化硅

D．层析液

下列症状中不适宜采用认知疗法进行治疗的是（）

A.中老年糖尿病、高血压问题

B.成人工作压力、人际关系问题

C.大学生恋爱、就业问题

D.青年人适应问题

E.儿童注意力不集中问题

用所给单词的适当形式填空。

1. My _____(big) problem is that I can't memorize the English new words.

2. His life_____(change) a lot in the last few years.

3. My grandfather used _____(swim) in the river when was young.

4. Would you mind my_____(shut) the door?

5. It often      (take) us two hours_____(do) our homework every day.

6. I used to be afraid of _____(speak ) in front of a group.

7. I am very hungry, because I_____(not have) my dinner yet.

8. We find it easy_____(learn) English well.

9. Don't give up_____( try) , you will make it in the end.

10. He didn't _____(use) to like tests, but now he likes them very much.

正圆柱体的高为10cm，底面半径为cm，那么，在圆柱体的表面，从A点到 D点的最短距离为（）。

A．9cm

B．2

C．4

D．10cm

收入预算要留有余地，预算要先保证基本工资.离退休费和日常办公经费等基本支出，体现的部门预算的原则是（）

A.合法性原则

B.稳妥性原则

C.完整性原则

D.科学性原则