问题 单项选择题

分馏系统短循环时,分馏系统各塔()。

A.应保持压力梯度

B.应保持温度梯度

C.应保持流量梯度

D.应保持液位梯度

答案

参考答案:A

阅读理解

阅读理解。

     Mrs. White, a fifty-four-year-old woman, lives in a small town. Her husband died several years ago. Her

son, Ron, works in an office in London. And her daughter lives in the same town with her, but she lives in her

husband's house. Only the old woman stayed in the old house by herself.

     One day Mrs. White received a letter from Ron. The young man missed her very much. He hoped she

would go to the capital soon. The woman was happy and decided to start the next morning. She took a bus

to the railway station and bought a ticket. Before she was going in, suddenly she remembered she had not

locked the gate of the house. As she forgot her daughter's telephone number, she hurried to the post office

and bought a stamp and an envelope (信封). In her letter she told her daughter to lock the gate right now.

then she put the envelope into the post box. At the entrance a man stopped her and said, "Your ticket, please."

Mrs. White had a look at her hand, and began to cry: she was holding the letter in her hand.

1. Ron missed his mother because ______. [ ]

A. he wanted her to look after him

B. she was too old to look after herself

C. he was afraid she would be ill at home

D. he thought she felt lonely at home

2. Mrs. White's husband has been dead ______. [ ]

A. before several years

B. for a few years

C. since last year

D. many years ago

3. Mrs. White decided to go to London ______. [ ]

A. by train

B. by bus

C. by plane

D. by ship

4. Mrs. White told her daughter to lock the gate because ______. [ ]

A. she was more careful than her

B. she knew where she lived

C. she only had a daughter

D. nobody else was to ready to help her

5. Mrs. White began to cry because ______. [ ]

A. the man didn't let her in

B. she had put the letter into the post box

C. she lost her letter

D. she had put the ticket in the envelope

多项选择题 X型题