问题 问答题 简答题

如何判断齿面出现疲劳点蚀的齿轮是否应该更换?

答案

参考答案:

齿轮出现轻微早期点蚀后,在使用中增大润滑油粘度和减小动载荷仍可继续使用。若继续发展到下列情况之一时,必须更换:点蚀区高度为齿高的30%,长度为齿长的40%;点蚀区高度为齿高的70%,长度为齿长的10%。

阅读理解

We know the kiss as a form of expressing love. But long before it became , it was customary in many countries to use it as an expression of respect. Some native Africans kiss the ground over which a chief has walked. Kissing the hand and foot has been a mark of respect from the earliest times.

The early Romans kissed the mouth or eyes as a form of noble greeting. One Roman emperor allowed his important nobles to kiss his lips, but the less important ones had to kiss his hands, and the least important ones were only allowed to kiss his feet!

Most likely the kiss as a form of affection can date back to ancient times when a mother would touch her child gently, just as a mother does today. It only remained for society to accept this as a custom for expressing affection between arms.

The first society where the kiss became accepted in marriage was in France. From France the kiss spread rapidly all over Europe. As marriage customs developed, the kiss became a part of the wedding ceremony. Today we regard it as an expression of love and tenderness. But there are still many places in the world where the kiss is part of formal ceremonies and is intended to show respect.  

46. According to the passage, kiss was earlier used as _________.

A. a custom                                                             B. an expression of love

C. an expression of respect                                        D. an expression of power

47. How did the early Romans show their greeting?

A. They would kiss the lips.                                      B. They kissed other’s hands.

C. Feet would be kissed to show their greeting.           D. They would kiss mouth or eyes.

48. What does the underlined word “affection” mean?

A. respect                                                                B. love

C. honor                                                                 D. worry

49. According to the text, which of the following is not using a kiss?

A. courtship                                                            B. greeting

C. sorrow                                                                D. affection

50. This passage mainly tells us that _____.

A. Introduction on how to kiss.

B. The different meanings of kiss from the ancient times to present days.

C. How to kiss each other in different countries.

单项选择题