地球约在（）年前出现可以进行光合作用的生物。

阅读理解

       Do you know why different animals or pests have their special colours? Colours in them seem to be

used mainly to protect themselves.

       Some birds like eating locusts, but birds cannot easily catch them. Why? It is because locusts change

their colours together with the change of the colours of crops. When crops are green, locusts look green.

But as the harvest time comes, locusts change to the same brown colour as crops have. Some other pests with different colours from plants are easily found and eaten by others. So they have to hide themselves for lives and appear only at night.

       If you study the animal life, you'll find the main use of colouring is protecting themselves. Bears, lions

and other animals move quietly through forests. They cannot be seen by hunters. This is because they have the colours much like the trees.

       Have you ever noticed an even more strange act? A kind of fish in the sea can send out a kind of very black liquid when it faces danger. While the liquid spread over, the enemies cannot find it. And it

immediately swims away. So it has lived up to now though it isn't strong at all.

1. From the passage we learn that locusts ________.

A. are small animals

B. are easily found by birds

C. are dangerous to their enemies

D. change their colours to protect themselves

2. How can pests with different colours from plants keep out of danger?

A. They run away quickly.

B. They change to the same colours as their enemies'.

C. They hide themselves in the day and appear at night.

D. They have to move quietly.

3. Bears and lions can keep safe because they ________.

A. have the colours much like the trees

B. move quickly

C. like brown and grey colours

D. live in forests

4. The kind of fish live up to now because ________.

A. it is very big and strong

B. the liquid it sends out helps it escape from its enemies

C. the liquid it sends out can kill its enemies

D. it swims faster than any other fish

5. Which is the best title for this passage?

A. The Change of Colours for Animals and Pests

B. Colours of Different Animals and Pests

C. The Main Use of Colours for Animals and Pests

D. Some Animals and Pests

对艾滋病的阐述正确的是（）

A.艾滋病病原体为人类免疫缺陷病毒

B.艾滋病病原体抵抗力很强

C.消毒剂很难将其杀灭

D.艾滋病可以通过空气传播

E.艾滋病可以通过一般接触传播

全球定位系统使用的实际意义是[ ]

A、使人们在野外不易迷失方向

B、使指南针精确度增加

C、只需一颗卫星便能覆盖全球

D、对静止的物体进行定位

使用以下______命令可以启动菜单设计器对菜单进行修改。

A．OPENMENU＜菜单文件名＞

B．MODIFY MENU＜菜单文件名＞

C．DO MENU＜菜单文件名＞

D．RUN MENU＜菜单文件名＞

活化颗粒细胞内芳香化酶：（）

A．雌激素 

B．孕激素 

C．雄激素 

D．FSH 

E．LH