为何说“肺为水之上源”，有何临床意义？

中利公司与小明公司订立了向小明公司长期供应茶叶的合同，大华公司与小明公司、中利公司于2001年10月1日订立了保证合同，大华公司为中利公司的债权提供担保，约定在100万元的债权额限度内就3个月内(10月1日至1月1日)发生的茶叶货款提供保证。后来小明公司资信状况恶化，大华公司遂于12月3日通知中利公司终止保证合同，此时债权额已经有50万元；中利公司于12月10日收到通知，此间债权又增加了20万元，到1月 1日期间届满，债权额已经达到了100万元。此时中利公司向大华公司主张保证责任，请问此时大华公司应对多少债权承担保证责任( )

A．100万元，大华不能单方解除合同，解除通知无效

B．50万元，通知发出之日为债权截止之日

C．70万元，通知到达之日为债权截止之日

D．85万元，大华公司应当解除通知到达后发生的债权的1/2承担保证责任

一个int类型的常量和一个byte类型的常量做加法，则其结果的类型为( )。

A．int

B．byte

C．char

D．long

The questions in this group are based on the content of a passage. After reading the passage, choose the best answer to each question. Answer all questions following the passage on the basis of what is stated or implied in the passage.

The complex life cycle of the Plasmodium protozoan, the causative agent of malaria, has contributed to the difficulty of devising effective public health measures to combat the disease. It took scientists centuries to deconstruct the basic relationship between protozoan, mosquito vector, and human host. Modern physiologists and epidemiologists are still working out the intricacies of malarial infection.

The disease is transmitted by the bite of a female Anopheles mosquito infected with the Plasmodium parasite. Only Anopheles mosquitoes are capable of transmitting the disease, and only females take blood meals from humans. To become infected with Plasmodium, the female mosquito takes a blood meal from a human carrying the parasite in his or her blood. Once ingested, the parasite matures in the mosquito’s gut for approximately a week, after which it migrates to the insect’s salivary glands. By mixing with the mosquito’s saliva, the parasite facilitates its transmission to a human host when the mosquito bites that human.

Once in a human’s bloodstream, the parasite travels to the human’s liver. At this initial stage, the Plasmodium parasite is called a sporozoite. Within the liver, the sporozoite can form 30,000 to 40,000 daughter cells, called merozoites, which are released into the host’s bloodstream at a later date, sometimes within a week of the initial infection and sometimes as much as several months later. The merozoites seek out and attach themselves to red blood cells, in which they incubate 8 to 24 daughter cells over the next two days. When the daughter cells are mature, the red blood cell ruptures and the new parasites are released into the bloodstream to seek out red blood cells of their own. Some of the new merozoites become male and female gametocytes; if these gametocytes are ingested by a mosquito feeding on the host’s blood, they will fertilize in the mosquito’s gut to produce new sporozoites, and the cycle will continue.

The symptoms that we associate with malaria--a high, recurring fever; joint pain; a swollen spleen--are caused by toxins released from the red blood cells ruptured by merozoites. The human spleen can destroy these infected blood cells, but the Plasmodium parasite counters this effect by increasing the stickiness of proteins on the blood cells’ surfaces so that the cells stick to the walls of blood vessels. If the sticky surface proteins affect a particularly large number of cells, the malaria can trans-form into a hemorrhagic fever, the most deadly form of malaria.

A further complicating factor in the natural history of malaria is the many variants of the Plasmodium protozoan. Scientists now recognize that malaria is caused by at least six different species: P. falciparum, P. vivax, P. ovale, P. malariae, P. knowesli, and P. semiovale. Of these species, P. falciparum accounts for the majority of infections and approximately 90 percent of malarial deaths in the world.

Based on the information given in the passage, which of the following would be most effective in preventing a person infected with malaria from developing a hemorrhagic fever ？（）

A. Surgical removal of the spleen

B. A medicine that prevents changes to the surface proteins of red blood cells

C. An effective vaccine against malaria

D. A potent pesticide that reliably kills the Anopheles mosquito without producing any negative consequences for the environment or for human health

E. A small infusion of a weaker variant of the Plasmodium protozoan that will then compete with the existing parasitic infection

张三的负债为5万元，总资产为20万元，可知其清偿比率为( )。

A．60%

B．65%

C．70%

D．75%

预冷塔的作用是什么？