问题 问答题 简答题

简述对制冷剂的一般要求?

答案

参考答案:

(1)常压下蒸发温度要低,在常温及普通低温范围内都能液化。

(2)冷凝压力不要太高,蒸发压力不要太低。

(3)单位容积制冷量大。

(4)临界温度要高,凝固点要低,汽化潜热要大,蒸气比容要小。

(5)对系统材料无腐蚀,与润滑油无化学反应,价格低廉,易于获取,无毒。

阅读理解

For five days, Edmonton's Downtown Park is transformed into one huge stage where artists are able to share their talents, and where people are able to celebrate and enjoy themselves .Since is beginning in 1980,the Edmonton Folk Music Festival has been commemorating(纪念)the true feeling of what folk music is all about and that's the traditional togetherness(友爱)that is felt when people gather to share stories and feelings through song.

This year will be the sixth year when volunteer Riedel will be offering up her time to the festival. "People coming off a busy spring and summer have a moment of relaxation." Riedel said. "It's really easy to relax, and it's great seeing family and friends have fun together." These families and friends come from all different kinds of musical tastes. People who take pleasure in Blues are there, so are people who love Bluegrass. This festival does its best to develop everyone's musical interests.

With so many years of experience, the festival has become a well-oiled machine, and does whatever it can to make attendees feel as comfortable as possible. There are free water stations throughout the venue(举办地)for people to fill up their travel cups. When people buy food, reusable dishes are given a $2 plate fee, but that is returned when the plate is brought back.

The festival has completely sold out of tickets, and in record time .But with big names such as Van Morrison and Jacob Dylan, it’s easy to see how that was going to happen. The festival has completely sold out of tickets, and in record time, so using the same Park and Ride system or Edmonton Transit is highly recommended .A bike lock-up area is provided and will be available Thursday until Sunday one hour before the gates open until 45 minutes after the gates close.

The Edmond Folk Music Festival begins on Wednesday, Aug 4 with Van Morrison plaything the special donation fund concert, and will finish up on Sunday,Aug 8.

小题1: The Edmonton Folk Music Festival is held mainly to ___________

A.gather people with different musical tastes.

B.remind people of the real sense of folk music.

C.exhibit the good voices of great talent in folk music.

D.collect old stories of folk music.小题2:Which of the following is TRUE according to the passenger?

A.Riedel has volunteered for the festival for at least developed 5 years.

B.It’s hard for people to appreciate Blues.

C.It costs people a little to fill up their cups from water station.

D.People have to pay a visit to for a plate of food.小题3:We can learn from passage that

A.people can get tickets easily for the festival.

B.the Edmonton Folk Music Festival is well organized .

C.driving one ‘s own car to the festival is highly recommended.

D.bikes are available at the festival from Wednesday to Sunday.小题4:What would be the best title for this passage?

A.Folk Music of Blues.

B.One Festival for All.

C.Festival for Family Gathering.

D.Edmonton’s Downtown Park

单项选择题 B1型题