在“探究摩擦力大小与哪些因素有关”的实验中，同学们提出了以下几种猜想：A．与物体质量大小有关；B．与物体间的接触面积大小有关C．与物体运动速度有关；D．与物体间接触面的粗糙程度有关实验中有一较长的水平

题干

在“探究摩擦力大小与哪些因素有关”的实验中，同学们提出了以下几种猜想：

A．与物体质量大小有关；B．与物体间的接触面积大小有关

C．与物体运动速度有关；D．与物体间接触面的粗糙程度有关

实验中有一较长的水平粗糙桌面、一个带构的长方体木块和一支弹簧测力计可供使用．

上一题下一题 0.0难度选择题更新时间:2019-05-20 08:19:09

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阅读材料,从每题所给四个选项（A、B、C和D）中选出最佳选项。

Jack works in a bookstore. Here is a note from his boss, Ben. Jack will decide what books to order（订购） according to the notes and the information about the books.

Hi Jack,

You must hand in the order list of books by the first working day of every month. The rules for choosing books are:

For textbooks:

※August is coming. We must have all textbooks, without thinking of other rules.

For books which are not textbooks:

※If more than 5 copies were sold last month, we choose them. But if there are 5 or more in stock(现货)，we do not make an order.

※If the wholesale(批发) prices are higher than ﹩75, we don't choose them. And we don't order anything whose retail(零售) price is higher than ﹩100.

The information about the books

Title: Homeland English

Publisher(出版社): Homeland Ltd

Wholesale price: ﹩110

Retail price: ﹩140

Textbook: Yes

Copies sold last month: 3

Copies in stock: 2

Title: How to Become Successful

Publisher: Founders Company Ltd

Wholesale price: ﹩25

Retail price: ﹩40

Textbook: No

Copies sold last month: 2

Copies in stock: 1

Title: Biology at a Glance

Publisher: New Times Publishing Ltd

Wholesale price: ﹩70

Retail price: ﹩95

Textbook: No

Copies sold last month: 18

Copies in stock: 3

Title: Good Health in 20 Days

Publisher: Oscar World Ltd

Wholesale price: ﹩50

Retail price: ﹩6 6

Textbook: No

Copies sold last month: 10

Copies in stock: 20

题干

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