Hardly could he _______this amount of wo

发布时间：2017-05-08 15:07 │ 来源：www.tikuol.com

题型：选择题

问题：

Hardly could he _______this amount of work in such a short time.

A．get through

B．get off

C．get into

D．get down

考点：序数词

题型：选择题

There is a policeman _____ the bus. He is watching the traffic.

A．in front of

B．in the front of

C．in the front

D．the front

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题型：选择题

某工程为一座大型钢结构工业厂房，建筑总面积为60000m²，主厂房结构为三层钢结构，屋檐高12m，柱网间距为12m×15m，屋面采用双层彩色压型钢板，工期为200天。承包方为劳务分包公司，大中专毕业生占管理人员的53%，技工、高级技工占员工总数的40%，缺乏大型工程施工的经验。

钢材是以铁为主要元素，含碳量为( )，并含有其他元素的合金材料。

A．0.01%～0.02%

B．0.02%～2.06%

C．2.06%～3.00%

D．3.00%～4.06%

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A pilot cannot fly a plane by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must use radar, an alternative way of navigating. Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving. The basic principle of radar is exemplified by what happens when one shouts in a cave. The echo of the sounds against the walls helps a person determine the size of the cave. With radar, however, the waves are radio waves instead of sound waves. Radio waves travel at the speed of light, about 300, 000 kilometers in one second. A radar set sends out a short burst of radio waves: Then it receives the echoes produced when the waves bounce off objects. By determining the time it takes for the echoes to return to the radar set, a trained technician can determine the distance between the radar set and other objects. The word "radar," in fact, gets its name from the term "radio detection and ranging." "Ranging" is the term for detection of the distance between an object and the radar set. Besides being of critical importance to pilots, radar is essential for air traffic control, tracking ships at sea, and for tracking weather systems and storms.

What is the main topic of this passage

A．The nature of radar.

B．Types of ranging.

C．Alternatives to radars.

D．History of radar.

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题型：选择题

AIS自动播发的船舶信息中包括船舶的（）信息。

A．静态

B．动态

C．与航行安全有关

D．以上全部

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题型：选择题

最优报价的确定

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