问题 问答题 简答题

为什么一般在发动机的配气机构中要留气门间隙?

答案

参考答案:

发动机工作时,气门因温度升高而膨胀,如果气门及其传动件之间在冷态时无间隙或间隙过小,则在热态下,气门及其传动件的受热膨胀势必引起气门关闭不严,造成发动机在压缩和作功行程中的漏气而使功率下降,严重时甚至不易启动,为了消除这种现象,通常在发动机冷态装配时,在气门与其传动机构中留有适当的间隙,以补偿气门受热后的膨胀量,这一间隙通常称为气门间隙。

阅读理解

Question: I have a one-year-old female bulldog, who has recently taken to biting my shoes when we are in the park and I’m on the mobile. She can be slightly aggressive and I’m starting to get worried and a bit annoyed. How do I stop her? ----Susan, London.

Answer: You need to get this problem under control before it could escalate (恶化). I always advise owners not to talk on the mobile phone when they go for a walk with their dogs, because they should be focusing on this time with their pets, but I know people have busy lives and need to make phone calls.

The behavior she is showing is either controlling or playfulness, but they both result from the same issue ---- you are not paying attention to her. If you must make phone calls while on a walk, try to still engage with your dog by speaking towards her, playing some sorts of game and so on. If that doesn’t work, you’ll have to try more of a training approach.

You will need a training line and some treats. Start your walk in the usual way, make a phone call, and when your dog starts displaying the undesired behavior, simply stop walking --- otherwise she will see it as a game. When she is calm and looking at you, or if she sits, give her a treat; then continue walking. If she starts up again, pick up the lead, gently pull it, and tell her “no”.  Then ask her to sit and give her a treat if she does.

The aim of this is to try to get her to forget how much fun it is biting your shoes. Do little sessions every day --- and try not to answer the phone if you know it’s going to be a long conversation. Be patient and good luck!

Remember that if an animal shows signs of distress or discomfort, an early visit to the vet is always recommended.

小题1:What is Susan complaining about in her question?

A.She doesn’t know how to make phone calls while walking a dog.

B.She has no idea how to get along well with her dog.

C.She gets worried that her dog is getting annoyed.

D.She finds her dog is getting a little aggressive.小题2:The probable reason why the pet dog bites its owner’s shoes is that ______.

A.the owner isn’t paying attention to her

B.the owner often makes trouble for the dog

C.the owner plays some dull games with her

D.the owner doesn’t like the pet dog any more小题3:The solution to dealing with the distress or discomfort of pets is to _____.

A.talk with them regularly

B.take them to see the vet

C.play games with them

D.let them bite your shoes小题4:How can Susan get her pet dog to forget the fun from biting her shoes?

A.By playing some sort of game with the pet dog.

B.By punishing the pet dog strictly.

C.By training her not to do so.

D.By leaving her at home.

单项选择题