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对人字拨杆的桅杆相交角度有什么要求？

答案

参考答案：

人字拨杆的两根桅杆相交的角度不宜太小和太大，一般为55°左右。角度太小，人字拨杆就不稳定，角度太大，桅杆的受力就大，就会降低起重的能力。

单项选择题

Not everyone in the world requires the same amount of living space. The amount of space a person needs around him is a cultural difference, not an economic one. Knowing your own psychological space needs is important because they ply affect your choices, including, for example, the number of bedrooms in the home. If you were brought up in a two child family and both you and your sister or brother had your own bedrooms, the chances are if you have two children or more, that you also will offer separate bedrooms for them. In America, for example, they train people to want to have their own rooms by giving them their own rooms when they are babies. This is very unusual in the world. In many other countries, the baby sleeps in the same bed with his parents or in bed near them.
The space in the home also shows a lot about psychological space needs. Some families gather closer to each other and the size of their house has nothing to do with it. Others have separate little corners where family members go to be alone.
Although it is true that psychological space needs are not decided by economic reasons, they sometimes have to be changed a little because of economic pressure. It is almost impossible, however, to completely change your psychological space needs.

The first sentence in Paragraph 1 "Not everyone in the world requires the same amount of living space" means ______.

A．Not two people need exactly the same amount of living space
B．Living space requirements are not always the same
C．The world requires the same amount of living space
D．Nobody needs a required amount of living space
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单项选择题

下列各项中，应当依法征收房产税的是( )。

A．农村的农副业生产用房

B．外商投资企业设在城市的生产用房

C．居民住宅区内业主共有的经营性房产

D．国家机关自用的房产
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