问题 问答题 简答题

车外圆时,车刀装得过高或过低,刀具角度会发生哪些变化?对加工有何影响?

答案

参考答案:

1)车刀装得过高将会使刀具的实际前角增大,实际后角减小;装得过低会使得刀具的实际前角减小,实际后角增大。

2)刀具的实际工作角度变化均改变了原设计值,偏离了刀具的最佳切削状态。刀具转得过高,会加大刀具后刀面与工件的摩擦;刀具装得过低,容易引起扎刀,对加工均不利。

阅读理解

阅读与回答问题(5小题, 每题2分,共10分)

Do you feel lonely when your best friend isn’t around? Of course, yes. Here’s our advice to you—and to all kids who feel lonely sometimes.

You may feel lonely at break or lunchtime when a best friend isn’t around—maybe because he or she moved to a different school or a different class. You want to have new friends, but how do you make them? Maybe it seems everybody else already has his or her friends. But remember, there’s always room for more friends.

Start by looking around your classroom—think about which kids you’d like to play with at break. Look for chances to say hi to them, smile, and be friendly. Offer to share something or express your appreciation (欣赏) to them. Invite someone to play with you or say, “Do you want to sit here?” in the lunchroom. When you’re at break, walk over to kids you want to play with, act friendly, and say “Hi, can I play, too?” or just join in.

If you have trouble doing this or if you’re feeling shy, ask your teacher to help you make new friends. Teachers are usually pretty good at matching up friends. The best way to make friends is to be a friend. Be kind, be friendly, share, say nice things, offer to help ---and pretty soon, you’ll have one, or two, or even more new friends.

You might still miss that special best friend. But when you see each other, you can share something you didn’t have before he or she left. You can introduce him or her to your new friends!

小题1: How do you feel when your best friend isn’t around you according to the passage?

 

小题2: Why do some kids feel lonely at break according to the writer?

小题3: What is the best way to make friends according to the writer?

小题4: Why do some kids need help from teachers to make friends according to the writer?

小题5: What should you do if you want to make more friends? (请自拟一句话作答)

 

多项选择题