Malaria parasites (寄生蟲) enter a person’s blood through a mosquito bite. These organisms travel to the liver. They grow and divide there. After a week or two, the parasites invade red blood cells and reproduce thousands of times. They cause the person’s body temperature to rise. They also may destroy major organs. People with malaria may suffer kidney failure or loss of red blood cells.

　　Some medicines are generally effective in preventing and treating malaria. They are designed to prevent the parasites from developing in the body. People die from malaria because they are not treated for the disease or the treatment is delayed.

　　21. According to the passage, we can infer that _________.

　　A) female mosquitoes don’t bite animals

　　B) female mosquitoes bite people for a substance that keeps blood flowing

　　C) malaria is found everywhere in the world

　　D) countries in Europe and North America have low malaria death rate

　　22. What is the right order in which mosquitoes grow?

　　a. Adult mosquitoes pull themselves out of the pupas and fly away.

　　b. The larvae change into creatures called pupas.

　　c. The insect leaves the eggs in any standing water.

　　d. The eggs produce worm-like creatures called larvae.

　　A) c, a, b, d B) d, c, b, a C) c, d, b, a D) d, b, c, a

　　23. According to the WHO, the organisms carried by mosquitoes __________.

　　A) are the food for larvae

　　B) have led to the death of millions of people in the world

　　C) invade red blood cells first and then destroy major organs

　　D) can enter a person’s brain through the mosquito’s bite