破波阻力产生的条件是().A.船型削瘦 B.船型丰满 C.必须存在自由表面 D.船舶

题型:单项选择题

问题:

破波阻力产生的条件是().

A.船型削瘦

B.船型丰满

C.必须存在自由表面

D.船舶航行速度大于20kn

考点:海船船员考试主推进动力装置主推进动力装置题库
题型:单项选择题

阅读理解。

     Some people think that they have an answer to the problems of automobile crowding and pollution in large

cities. Their answer is the bicycle, or bike.

     In a great many cities, hundreds of people ride bicycles to work every day. In New York City, some bike

riders have even formed a group called "Bike for a Better City". They claim that if more people rode bicycles

to work there would be fewer automobiles in the downtown section of the city and therefore less dirty air

from car engines.

     For several years this group has been trying to get the city government to help bicycle riders. For example,

they want the city to paint special lanes-for bicycles only-on some of the main streets, because when bicycle

riders must use the same lanes as cars, there may be accidents. "Bike for Better City" feels that if there were

special lanes, more people would use bikes.

     But no bicycle lanes have been painted yet. Not everyone thinks it is a good idea. Taxi drivers don't like the

idea-they say it will slow traffic. Some store owners on the main streets don't like the idea-they say that if there

is less traffic, they will have less business. And most people live too far from downtown to travel by bike.

     The city government has not yet decided what to do. It wants to keep everyone happy. On weekends,

Central Park-the largest open place in New York-is closed to cars, and the roads may be used by bicycles only.

But "Bike for a Better City" says that this is not enough and keeps fighting to get bicycle lanes downtown. Until

that happens, the safest place to bicycles may be in the park.

1. The underlined word"automobiles" in the second paragraph means _____.

A. trains

B. cars

C. planes

D. ships

2. Which of the following is TRUE according to the passage?

A. Special lanes are needed on every street.

B. The Central Park is closed to cars on weekdays.

C. "Bike for a Better City" members ride bicycles to work.

D. Accidents won't happen if cars and bikes are on different lanes. 

3. No bicycle lanes have been painted yet because _____.

A. the idea hasn't been accepted by all

B. the main streets are not wide enough

C. the city government can't help to paint the lanes

D. there's no need for most people to travel by bike

4. This passage is mainly about _____.

A. city problems and "Bike for a Better City"

B. "Bike for a Better City" and the city government

C. the government's idea on traffic and city pollution

D. a suggestion on the city problems of traffic and pollution

题型:单项选择题

现有两只阻值相等的电阻R1、R2,一个电压不变的电源,导线若干。试用以上器材,以不同的连接方式分别接入如图甲、乙两个虚线框中的A,B,C,D四个接线柱上,而且甲、乙两种不同的接法都能同时满足:开关S合上时电流表的示数是S断开时电流表的示数的两倍。

题型:单项选择题

诊断和鉴别诊断慢性前列腺炎哪项不适合()

A.尿常规检查

B.前列腺液常规镜检

C.前列腺直肠指诊

D.前列腺液细菌培养

E.前列腺穿刺活检

题型:单项选择题

心动周期中,心室血液充盈主要是因为()。

A.心房收缩的挤压作用

B.血液的重力作用

C.骨骼肌的挤压作用

D.胸内负压促进静脉回流

E.心室舒张的抽吸作用

题型:单项选择题

下列不属于破坏自然资源的犯罪有()

A、非法占用耕地罪

B、非法采伐森林罪

C、非法捕捞水产品罪

D、擅自进口固体废弃物罪

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