问题
问答题 论述题
试述安全阀的作用是什么？
答案
参考答案：
安全阀是压力容器的安全附件之一。容器在正常的工作压力下运行时，安全阀保持严密不漏，而当容器压力超过规定值时，它能自行开启泄压，以防止容器或管线受破坏；当容器内压力泄压至正常时，它又能自行关闭停止排泄。同时，安全阀在泄压排放介质量的流速较高，响声较大，也起到了自动报警作用。
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试述安全阀的作用是什么？
参考答案：
安全阀是压力容器的安全附件之一。容器在正常的工作压力下运行时，安全阀保持严密不漏，而当容器压力超过规定值时，它能自行开启泄压，以防止容器或管线受破坏；当容器内压力泄压至正常时，它又能自行关闭停止排泄。同时，安全阀在泄压排放介质量的流速较高，响声较大，也起到了自动报警作用。
| 阅读理解。 |
| Bill Clinton took office (就职) on January 20th, 1993 and became the 42nd U.S. president (总统). He is the first U.S. president who was born after World War II (第二次世界大战). He is also one of the youngest of all U.S. presidents. Clinton was born in a poor family in 1946. Three months before he was born, his father William Blats died. When he was small, his mother remarried (又嫁给) Norger Clinton, so the boy's family name changed. In the summer of 1963, Clinton won a drama contest (戏剧比赛), so he was given a chance to visit the city of Washington (华盛顿). During his visit he met President Kennedy in the White House. From that time on, he made up his mind (决心) to become a president. |
| 1. How old was Clinton when he became the 42nd U.S. president ? |
[ ] |
| A. About forty. B. Over fifty. C. Forty-seven. D. Thirty |
| 2. Clinton's father, William Blats, died _______. |
[ ] |
| A. before 1945 B. before Clinton was born C. before World War II D. when Clinton was young |
| 3. Why was the boy's family name changed? Because _______. |
[ ] |
| A. he became a president B. his family was poor C. his mother was ill D. his mother remarried |
| 4. In 1963 Clinton came to the city of Washington _______. |
[ ] |
| A. to take part in a drama contest B. to have a talk with Kennedy C. for a visit D. for his holidays |
| 5. This passage is about _______. |
[ ] |
| A. Bill Clinton B. Norger Clinton C. Kennedy D. William Blats |