The government-run command post in Tunis is staffed around the clock by military personnel, meteorologists and civilians. On the wall are maps, crisscrossed with brightly colors arrows that painstakingly track the fearsome path of the enemy.
　　What kind of invader gives rise to such high-level monitoring? Not man, not beast, but the lowly desert locust(蝗虫). In recent months, billions of the 3-inch-long winged warriors have descended on Algeria, Libya, Morocco and Tunisia, blackening the sky and eating up crops and vegetation. The insect invasion, the worst in 30 years, is already creating great destruction in the Middle East and is now treating southern Europe. The current crisis began in late 1985 near the Red Sea. Unusually rainy weather moistened the sands of the Sudan, making them ideal seedbed for the locust, which lays its eggs in the earth. The insect onslaught threatens to create yet another African famine. Each locust can eat its weight (not quite a tenth of an ounce) in vegetation every 24 hours. A good-size swarm of 50 billion insects eats up 100,000 tons of grass, trees and crops in a single night.
　　All ﹩150 million may be needed this year. The U.S. has provided two spraying planes and about 50,000 gal. of pesticide. The European Community has donated ﹩3.8 million in aid and the Soviet Union, Canada, Japan and China have provided chemical-spraying aircraft to help wipe out the pests. But relief efforts are hampered by the relative mildness of approved pesticides, which quickly lose their deadly punch and require frequent replications. The most effective locust killer dieldrin has been linked to cancer and is banned by many Western countries and some of the affected African nations. More than 5 million acres have been dusted with locust-killing chemicals; another 5 million will be treated by the end of June.
　　On May 30, representatives of Tunisia, Algeria, Libya, Morocco and Mauritania will meet in Algiers to discuss tactics to wipe out the ravenous swarms. The move is an important step, but whatever plan is devised, the locust plague promised to get worse before the insects can be brought under control.
The main idea of the first sentence in the passage is that ______.

A．the command post is stationed with people all the time.

B．the command post is crowded with people all the time.

C．there are clocks around the command post.

D．the clock in the command post is taken care of by the staff.

The favorable breeding ground for the locust is ______.

A．rich soil.	B．wet land
C．paces covered crops and vegetation	D．the Red Sea

People are alert at the threat of the locust because ______.

A．the insects are likely to create another African famine.

B．the insects may blacken the sky.

C．the number of the insects increases drastically.

D．the insects are gathering and moving in great speed.

Which of the following is true?

A．Once the pesticides are used, locust will die immediately.

B．Relief efforts are proved most fruitful due to the effectiveness of certain pesticides.

C．Dieldrin, the most effective locust killer, has been widely accepted in many countries.

D．Over 10 million acres of affected area will have been treated with locust-killing chemicals by the end of June.

The purpose for affected nations to meet in Algiers on May 30 is ______.

A．to devise anti-locust plans.

B．to wipe out the swarms in two years.

C．to call out for additional financial aid from other nations.

D．to bring the insects under control before the plague gets worse.