[单项选择]往复式压缩机停机时，操作步骤有（1）关闭出口阀（2）停机（3）关闭入口阀（4）跑油，正确的操作顺序是（）。
A. （2）、（1）、（3）、（4）
B. （1）、（2）、（3）、（4）
C. （2）、（1）、（4）、（3）
D. （3）、（2）、（1）、（4）

{{B}}Stress in College{{/B}}
Most students in US colleges are just plain stressed out, from everyday worries about grades and relationships to darker thoughts of suicide, according to a poll of undergraduates from coast to coast. The survey was conduced for the Associated Press and MTVU, a television network available at many colleges and universities.
{{B}}Students’ Stress Problem{{/B}}
Four in 10, students say they endure stress often. Nearly one in five say they feel it all or most of the time. But most are bearing it. Nearly 60% in the survey say they enjoy life.
The majority cite classic stress symptoms including trouble concentrating, sleeping and finding motivation. Most say they have also been disturbed, worried, too tired to Work. "Everything is being piled on at once," said Chris Curran, a junior at the Albany College of Pharmacy (制药) in Albany,
A. Eye problem.
B. Eating problem.
C. Concentration problem.
D. Breath problem.