屋面防水工程，沥青防水卷材采用空铺(点粘、条粘法)法施工，短边搭接宽度应为_____

魏源在《海国图志》中阐述了“师夷长技以制夷”的思想。他所说的“长技”在19世纪中期已经出现的是[ ]

A．电话　　　　　　　　

B．火车

C．电视  

D．飞机

个人和单位的奖励项目是什么？

OTDR主要技术指标中的反射率精度为（）。

A.±2dB

B.±4dB

C.±6dB

D.±8dB

仲裁监督

If you left your book on the table overnight, you would find the following morning that it was still exactly where you had left it, provided nobody had moved it. If a ball is made to roll on a very smooth surface, it will roll a long distance unless something stops it or changes its direction. This tendency of an object to remain at rest unless something moves it and to continue moving unless something stops it is known as the Law of Inertia.

The following examples show the truth of this law.

a. Put a table-cloth on a table and arrange a pile of books on it. Hold one edge of the table-cloth and pull it quickly. The table-cloth will come off, leaving the pile of books undisturbed.

b. Place a small piece of cardboard on an open jar and place a coin on it directly over its mouth. Use one finger to flick the piece of cardboard away. You will notice that the coin drops into the jar.

c. Sitting in a car which starts suddenly, you feel you are jerked backwards. In fact, you are not jerked backwards. Your lower half, which is in contact with the cushion, is forced to move forward with the car, and the upper part of your body, which remained at rest, is left behind.

In the second example, when the cardboard is flicked away, the coin will ()

A. drop into the jar

B. cover the mouth

C. stay on the cupboard

D. move into your hand