The usual way to ensure reliable delivery is to provide the (71) with some feedback about what is happening at the other end of the line. Typically, the protocol calls for the receiver to send back special (72) flame bearing positive or negative (73) about the incoming frames. If the sender receives a positive acknowledgement about a frame, it knows the frame has arrived safely. On the other hand, a negative acknowledgement means that’ something has gone wrong, and the frame must be transmitted again.

An additional complication comes from the possibility that hardware troubles may cause a flame to (74) completely. In this case, the receiver will not react at all, since it has no any reason to react. It should be clear that a protocol in which the sender transmits a frame and then waits for an acknowledgement, positive or negative, will hang forever if a frame is ever lost due to, for example, (75) hardware.

（74）处应填（）。

A．vanish

B．vary

C．appear

D．incline

根据句意、汉语或首字母和英文释义写出单词。

1. Many Chinese _______(官员) are still working hard for people in

    Sichuan because of the terrible disaster.

2. Tonny plays an important _______ (角色) in his family.

3. Now please let me _______ (介绍) myself to you , I'm Anita.

4. We must learn to c_______ our feelings when we hear or

    see very good or bad things.

5. How much p______ money do you get from your parents every week?

6. If your are ill, please take this m_______ three times a day and you will be well soon.

7. Many of our patients are so poor that they can't a________

   (have enough money to buy or to do something) to travel to hospital.

8. Everyone was very generous and we had a lot of support from

    local b_______ (organizations that make money by selling goods or services)

9. The harder you study, the more k_______ (information and

    understanding in the mind)you will get.

10. The f_______(people who like somebody or something very much)

     of the pop star are very excited now.