户外架空

室内汇流排

电气元件连接

绝缘导线线芯

配电柜、箱内连接

engagement

customary

social

inform

invitation

advance

absence

heavily

associate K. expected L. assumes M. habitual N. arise O. communicates In the United States, it is not 1 to telephone someone very early in the morning. If you telephone him early in the day, while he is shaving or having breakfast, the time of the call shows that the matter is very important and requires immediate attention. The same meaning is attached to telephone calls made after 11: 00 p. m. . If someone receives a call during sleeping hours, he 2 it's a matter of life and death. The time chosen for the call 3 its importance. In 4 life, time plays a very important part. In the U. S. A., guests tend to feel they are not highly regarded if the 5 to a dinner party is extended only three or four days before the party date. But it is not true in all countries. In other areas of the world, it may be considered foolish to make an appointment too far in 6 because plans which are made for a date more than a week away tend to be forgotten. The meaning of time differs in different parts of the world. Thus, misunderstandings 7 between people from cultures that treat time differently. Promptness is valued 8 in American life, for example. If people are not prompt, they may be regarded as impolite or not fully responsible. In the U. S. no one would think of keeping a business 9 waiting for an hour, it would be too impolite. A person who is 5 minutes late is 10 to make a short apology. If he is less than 5 minutes late, he will say a few words of explanation, though perhaps he will not complete the sentence.

户外架空

绝缘导线线芯

室内汇流排

配电柜、箱内连接

灯具连接线

新闻

新的

新鲜的

(AB) k =A k B k

|A|=-|A|

A 2 -B 2 =(A-B)(A+B)

若A可逆，k≠0，则(kA) -1 =k -1 A -1 .