活塞顶离曲轴中心最大距离时的位置称为（）。A、上止点 B、下止点 C、压缩比 D、燃

我国受夏季风影响长达5个月的地区有两广地区和（），西藏自治区东南部和（）受夏季风影响的时间有4个月。

患者男，45岁。1个月前觉上腹不适，疼痛，食欲减退，并有反酸、嗳气，服抗酸药未见好转，3天前出现黑便。近1个月来体重下降4kg。

为尽快明确诊断，首选下列哪项检查（）。

A.胃酸测定

B.胃镜检查

C.X线钡餐

D.B型超声波

E.粪便隐血试验

某车间需要用一台车床和一台铣床加工A、B、C、D四个零件。每个零件都需要先用车床加工，再用铣床加工。车床与铣床加工每个零件所需的工时（包括加工前的准备时间以及加工后的处理时间）如下表：若以A、B、C、D零件顺序安排加工，则共需32小时。适当调整零件加工顺序，可使所需总工时最短。在这种最短总工时方案中，零件A在车床上的加工顺序安排在第（）位，四个零件加工共需（）小时。

A．1

B．2

C．3

D．4

For well over a thousand years, smallpox was a disease that everyone feared. The disease killed much of the native population in South America when the Spanish arrived there in the early sixteenth century. By the end of the eighteenth century, smallpox was responsible for about one in ten deaths around the world. Those who survived the disease were left with ugly scars on their skin.

It had long been well known among farmers that people who worked with cows seldom caught smallpox; instead, they often caught a similar but much milder disease called cowpox (牛痘) . A British doctor called Jenner was extremely interested in this, and so he studied cowpox. He believed that, by vaccinating (给接种疫苗) people with the disease, he could protect them against the much worse disease smallpox. In 1796, he vaccinated a boy with cowpox and, two months later, with smallpox. The boy did not get smallpox. In the next two years, Jenner vaccinated several children in the same way, and none of them got the disease．

News of the success of Jenner’s work soon spread. Vaccination soon became a common method to protect people against other diseases caused by virus, such as rabies (狂犬病), and vaccines were sent across the world to the United States and India.

It took nearly two centuries to achieve Jenner’s dream of getting free of smallpox from the whole world. In 1967, the world Health Organization (WHO) started a great vaccination program, and the last known case of smallpox was recorded in Somalia in 1977. The story of vaccinations does not end there, however. There are many other diseases that kill more and more people every year. Besides, many new diseases are being discovered. The challenge for medical researchers will, therefore, probably continue for several more centuries

小题1:Smallpox was so serious that _________________ by the end of l8th century

A．its death rate was up to ten percent

B．those who caught it were certain to die

C．one in ten people in the world died of smallpox

D．one in ten deaths in the world was caused by smallpox小题2:Edward Jenner discovered that vaccination with cowpox could ____________.

A．make smallpox much milder

B．stop people from getting smallpox

C．protect people against any disease

D．prevent people’s scars after smallpox小题3:Which of the following statements is NOT TRUE?

A．The first experiment with cowpox was made by a British doctor.

B．After 1977 smallpox disappeared around the world according to WHO.

C．Vaccination had existed among ordinary farmers before being discovered.

D．Vaccination can be used to protect people in the world against not only smallpox.小题4:The author of the passage thinks that _________________.

A．vaccinations bring many new problems

B．vaccinations end the spread of diseases

C．there is a long way to go to fight against diseases

D．there is a long way to go to discover new diseases

国家税务系统的政府采购项目实行（）双重管理。（）

A.目录与程序

B.程序与限额

C.限额与数额

D.目录与限额