人类发现的最古老的人类化石是“__________”。

某温带草原里有鸟、昆虫、猫头鹰、蛇和鼠等6种动物，它们相互之间的关系是：①猫头鹰捕食蛇、鼠、鸟；②昆虫、鸟和鼠以植物为食；③蟾蜍和鸟捕食昆虫；③蛇吞食蟾蜍和鼠．

（1）把下列的食物网补充完整，以表示各生物间的关系．

鸟

植物→昆虫→蟾蜍→蛇→猫头鹰

鼠

（2）此食物网中含有______条食物链．

（3）若此生态系统受到有毒物质的污染，那么在体内积存污染物最多的生物是______．

（4）由于某种原因，鼠大量减少．但猫头鹰的数量变化不大，这说明______．

阅读理解。

     Scientists say illegal logging is threatening one of Mexico's most famous insects. Satellite pictures show

large wooded areas have been cleared from the central Mexican state of Michoacan. The forests are the winter

home for millions of monarch butterflies. The butterflies go there each year to reproduce. After reproducing,

the adult butterflies die, but their young return to the home of their parents each spring.

     The American space agency released the relevant satellite pictures last month. The images show the Monarch

Butterfly Biosphere Reserve. A Mexican law protects trees growing in the area. The images show that about

four hundred and forty-five hectares have been cleared since 2004. Scientists say that, if the clearing continues,

monarch butterflies are unlikely to continue using the Reserve as their winter home.

     For thousands of years, the butterflies have been flying to the same forests. Their trip begins along the border

of Canada and the northeastern United States. The insects fly about eighty kilometers a day. They reach central

Mexico after about sixty days. No one is sure why the brightly coloured orange and black butterflies chose these

forests. However, scientists believe the area might offer the right mix of wetness and cool weather to keep the

insects alive through the winter.

     Lincoln Brower is a professor of biology at Sweet Briar College in Virginia. He has been studying monarch

butterflies for fifty-two years. He says they have been migrating along the same path for about ten thousand

years. People in Mexico have compared the arrival of the butterflies to dark cloud-like formations (阵式) filling

the air. The monarchs arrive in such large numbers that they sometimes cover whole trees.

     Mexico's President ordered special protection for the Monarch Butterfly Biosphere Reserve eight years ago.

The Mexican government has struggled to enforce (强制) the order. Although illegal logging has become one

way for poor people to earn money, other Mexicans are fighting to protect the butterflies' home.

1. What would be the BEST title for the text?

A. Illegal Clearing of Forests Threatens Winter Home of Monarch Butterflies

B. The Forests are the Winter Home for Monarch Butterflies

C. Monarch Butterflies Like the Winter Home in the Forests

D. Protecting the Forests Can Protect Monarch Butterflies

2. Why are the forests called the winter home for millions of monarch butterflies? Because each winter

    the butterflies travel there to _____.

A. avoid cold

B. look for food

C. sleep

D. produce young

3. Why did monarch butterflies choose the forest as their winter home?

A. It has many trees.

B. It has the appropriate environment for them.

C. It is easy to get to.

D. We don't know.

4. The underlined word "migrating" in paragraph 4 is closest in meaning to "_____".

A. going to live in another area or country, especially in order to find food

B. travelling regularly from one part of the world to another

C. changing from one place or position to another

D. starting using an area again as a place to live

5. What can be inferred from the last paragraph? 

A. Mexico has nothing but forests.

B. Most people in Mexico are poor.

C. All Mexicans are destroying the butterflies' home.

D. Some poor people in Mexico often break the law.

PTA浆料混合罐搅拌器停运的联锁条件是（）。

A、PTA浆料混合罐液位高报

B、PTA浆料混合罐液位低低报

C、PTA浆料螺杆输送器停运

D、PTA日料仓料位低