选择性髂内动脉造影术的适应证有哪些（） A.原发于盆腔的血管性疾病 B.盆腔肿瘤 C

有如下的运算符重载函数定义：double operator+(inti,intk){return double(i+k);} 但定义有错误，对这个错误最准确的描述是( )。

A．+只能作为成员函数重载，而这里的+是作为非成员函数重载的

B．两个int型参数的和也应该是int型，而这里将+的返回类型声明为double

C．没有将运算符重载函数声明为某个类的友元

D．C++已经提供了求两个int型数据之和的运算符+，不能再定义同样的运算符

In today's world, almost everyone knows that air pollution（污染）and water pollution are harmful to people's health. However, not all the persons know that noise is also a kind of pollution, and that is harmful to human health, too.

People who work and live under noisy conditions usually become deaf（聋）. Today, however, scientists believe that 10 percent of workers in Britain are being deafened by the noise where they work. Many of the workers who print newspapers and books, and who weave（织）cloth become deaf. Quite a few people living near airports also become deaf. Recently it was discovered that many teenagers in America could hear no better than 65-year-old persons, for these young people like to listen to pop music and most of pop music is a kind of noise. Besides, noise produced by jet planes or machines will make people's life difficult and unpleasant, or even make people ill or even drive them mad.

It is said that a continuous noise of over 85 decibels（分贝）can cause deafness. Now the governments in many countries have made laws to control noise and make it less than 85 decibels.

In China, the government is trying to solve not only air and water pollution problems but also noise pollution problems.

小题1: The text is mainly about _________ .

A．air pollution

B．noise pollution

C．water pollution

D．world pollution小题2:According to the text, a continuous noise of _______ decibels can make people deaf.                                                                

A．less than 85

B．less than 65

C．more than 85

D．about 65小题3:10 percent of the workers in Britain are being deafened because_______________ .

A．they are too busy to listen to others' talk

B．they often listen to pop music

C．they live near airports

D．they are working in noisy places小题4:The government of China is trying to solve ____________ .

A．air, water and noise pollution

B．only air and water pollution

C．only water pollution

D．only air pollution

真空电子束焊的主要优点有（）。

A、电子束穿透能力强，焊缝深宽比大。

B、焊接速度快，热影响区小，焊接变形小。

C、特备适合活泼金属的焊接。

D、需填充材料。

机床局部或移动照明必须采用（）安全电压。

A、12V或6V

B、110V或220V

C、36V或24V

D、380V或220V

垫球的击球点位于腹前（）。