已知地球表面陆地面积 与海洋面积的比约为 3:7,如果宇宙中飞来一块陨石落在地球

题型:填空题

问题:

已知地球表面陆地面积 与海洋面积的比约为 3:7,如果宇宙中飞来一块陨石落在地球上,则落在陆地上的概率是(    )。

考点:概率的意义
题型:填空题

0.01级电压互感器在20%额定电压时的比差应不大于()。

A.±0.02%

B.±0.04%

C.±0.015%

D.±0.03%

题型:填空题

下列说法正确的是()。

A.业主应编制并随时更新一套完整的工程竣工记录,如实记载竣工的准确位置、尺寸和已实施工作的详细说明,并将竣工记录保存在现场

B.承包商应负责绘制并向雇主提供工程的竣工图,表明整个工程的施工完毕的实际情况,提交雇主根据合同"承包商文件"条款的规定进行审核

C.承包商应取得雇主对图纸的尺寸、基准体系、及其他相关细节的同意

D.在竣工试验开始前,承包商应向雇主提供暂行的操作和维修手册

题型:填空题

Nowadays, it is possible to travel to distant parts of the globe in several hours. This can result in the traveler ending up in a part of the world where time is different from his or her own “body clock” ,which control our sleep patterns.

If we travel east or west by more than four time zones (hours) then we will usually be affected.

In the past when people traveled by sea, there was enough time for the body to adjust to the local time, but with the advent of modern high speed aircraft the body does not have time to adjust. Therefore, there is the term “jet lag(时差反应)”. It normally takes one day per time zone (hour) for the body to adjust to its new surroundings.

The effects of jet lag are usually tiredness and insomnia (失眠) but can also include: poor concentration, nausea (恶心) ,vomiting (呕吐), constipation (便秘) and general malaise (不舒服). The effects are made worse by alcohol.

Sleeping while flying may help to reduce the symptoms (症状) of jet lag, but long periods of immobility aboard aircraft can make the traveler feel numb(麻木的) in the legs. The following are some other tips of reducing the symptoms of jet lag:

①Avoid traveling when you are already tired and rest before departure.

②Stopovers on long flights may be helpful.

③A relaxed flight is important.

④Sleeping tablets will help you to sleep and be correspondingly alert (相对警惕的) during the next day, but they do not speed up adjustment to the new time zone.

⑤Remember the actual traveling time will usually be at least twice the actual time spent in the air since it will include traveling to and from and hanging around in airports.

⑥Avoid heavy commitments on the first day after arrival.

72. The following are the effects of jet lag EXCEPT _____.

A. tiredness          B. coughing           C. insomnia           D. vomiting

73. The word “immobility” in the fifth paragraph means “_____”.

A. stillness           B. movement         C. activity             D. happiness

74. We can reduce the symptoms of jet lag by _____.

A. drinking some alcohol           B. keeping ourselves awake

C. taking some medicine            D. sleeping while flying

75. What is the main purpose of the passage?

A. To suggest people travel by sea instead of by air.        

B. To tell people the effects of jet lag.

C. To give people some advice about reducing the symptoms of jet lag.

D. To tell people about their body clock.

题型:填空题

下列成分不是HBV复制所必需的是()

A.HBsAg

B.HBcAg

C.HBeAg

D.P蛋白

E.X蛋白

题型:填空题

调速阀属于()类。

A.方向控制阀

B.压力控制阀帽

C.流量控制阎

D.运动控制阀帽

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