触诊胸部皮下气肿的部位，可出现A．摩擦感 B．反跳痛 C．握雪感 D．压痛 E．揉面

汽轮机启动时，阀门控制方式为单阀，启机一天后，应将单阀切为（）。

骨干IP网在SoftSwitch结构位于（）。

微积分产生可以归结为哪四类情况？

About fifty years ago, when television first came out, people thought that radio was no longer useful. Television has both sounds and images（影像）. It is much more real and interesting to watch television than to listen to the radio.

However, fifty years later radio is still very popular and it will be here for a long time. One reason is that we don’t need to see an image when we listen to the music on the radio. In fact, listening with your eyes closed is the best way to listen to a piece of music. You can imagine yourself on a sandy beach or up high on a mountain. In other words, you can create your own images. Moreover, while listening to the radio, you don’t have to take your eyes off your work. For example, you can listen to the radio and drive at the same time. Or you can read a book and listen to the radio. Television, on the other hand, doesn’t have this advantage.

A radio is much smaller than a television. You can take a radio anywhere and turn it on anytime you want. In a quiet place you can use headphones to listen to the news or music on the radio. In this way you won’t disturb anybody.

Moreover, a radio is much cheaper than a television. For less than $ 20 you can buy a small radio and have fun with it.

小题1:What is the passage mainly about?

A．Music.

B．Radio.

C．Sound.

D．Television.小题2:People like to watch TV because _______.

A．it has headphones to listen to the news

B．they can drive while watching TV

C．it has both sounds and images

D．they can watch with their ears小题3:We learn from the passage that _______.

A．people can take a radio anywhere and turn it on anytime

B．television came out 50 years ago and it is useless now

C．a radio is more expensive than a television

D．people can use headphones to read books

在通货膨胀的初期，为了防范通货膨胀风险，公司应当签订固定价格的长期销售合同。