嫦娥一号卫星的微波探测仪可探测“月壤”发出的频率3.0 GHz、7.8 GHz、

What the doctor warned us is that the _____ sleep may cause anger，poor memory and poor

concentration. [ ]

A. want in

B. plenty of

C. lack in

D. lack of

试述XT—12型通井机绞车刹车机构的工作原理

Shopping habits in the United States have changed greatly in the last quarter of the 20th century. 1 in the 1900s most American towns and cities had a Main Street.Main Street was always in the heart of a town.This street was 2 on both sides with many 3 businesses.Here, shoppers walked into stores to look at all sorts of merchandise: clothing,furniture,hardware,groceries. 4 ,some shops offered 5 .These shops included drugstores, restaurants, shoerepair stores, and barber or hairdressing shops. 6 in the 1950s, a change began to 7 .Too many automobiles had crowded into Main Street 8 too few parking places were 9 shoppers.Because the streets were crowded, merchants began to look with interest at the open spaces 10 the city limits.Open space is what their cardriving customers needed.And open space is what they got 11 the first shopping centre was built.Shopping centres, or rather malls, 12 as a collection of small new stores 13 crowded city centres. 14 by hundreds of free parking space, customers were drawn away from 15 areas to outlying malls.And the growing 16 of shopping centres led 17 to the building of bigger and betterstocked stores. 18 the late 1970s,many shopping malls had almost developed into small cities themselves.In addition to providing the 19 of onestop shopping, malls were transformed into landscaped parks, 20 benches,fountains,and outdoor entertainment.

1.A.As early as B.Early C.Early as D.Earlier

2.A.built B.designed C.intented D.lined

3.A.varied B.various C.sorted D.mixed up

4.A.Apart from B.However C.In addition D.As well

5.A.medical care B.food C.cosmetics D.services

6.A.suddenly B.Abruptly C.Contrarily D.But

7.A.be taking place B.take placeC.be taken place D.have taken place

8.A.while B.yet C.though D.and then

9.A.available for B.available to C.used by D.ready for

10.A.over B.from C.out of D.outside

11.A.when B.while C.since D.then

12.A.started B.founded C.set up D.organized

13.A.out of B.away from C.next to D.near

14.A.Attracted B.Surprised C.Delighted D.Enjoyed

15.A.inner B.central C.shopping D.downtown

16.A.distinction B.fame C.popularity D.liking

17.A.on B.in turn C.by turns D.further

18.A.By B.During C.In D.Towards

19.A.cheapness B.readiness C.convenience D.handiness

20.A.because of B.and C.with D.provided

监督检查部门在依法对从事不正当竞争行为的经营者实施行政处罚时，无法计算经营者违法所得的，可以根据违法情节处以违法经营额1倍以下的罚款。

设f(x，y)与g(x，y)在区域D上连续，而且f(x，y)＜g(x，y)，则二重积分与的大小关系是前者比后者().