起重机承载能力的计算方法有许用应力法和极限状态法两种。许用应_爱下问搜题

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问题填空题

起重机承载能力的计算方法有许用应力法和极限状态法两种。许用应力是按材料的（）考虑一定的安全储备来获得。

答案

参考答案：强度极限

单项选择题

D

What are you going to do if you are in a burning house How will you escape Do you know how to save yourself Please read the following passage.
Escaping a fire is a serious matter. Knowing what to do during a fire can save your life. It is important to know the ways you can use and show them to everyone in the family, such as stairways and fire escapes, but not lifts.
From the lower floors of the buildings, escaping through windows is possible, learn the best way of leaving by windows with the least chance of serious injury.
The second floor window is usually not very high from the ground. An average(平均高度的) person, hanging by the finger-tips will have a drop of about six feet to the ground. It is about the height of an average man. Of course, it is safer to jump a short way than to stay in a burning building.
Windows are also useful when you are waiting for help. Be sure to keep the door closed. Or smoke and fire may be drawn into the room. Keep your head low at the window to be sure you get fresh air rather than smoke that may leaked (渗) into the room.
On a second or third floor, the best windows for escape are those that open onto a roof. From the roof a person can drop to the ground more safely. Dropping onto cement(水泥) might end in injury. Bushes(灌木丛) and grass can help to break a fall.

Open the window so that ______ if the building is on fire.

A．you can get fresh air

B．you can call for help

C．you can easily jump off

D．you can be seen first

单项选择题

某家庭以30万元购买了一套住宅，银行为其提供了20年期的住房抵押贷款，该贷款的年利率为9%，按月等额还款，如果该家庭于第6年年初一次提前偿还贷款本金7万元，则从第6年开始的抵押贷款月还款额将减少（）元。

A．544.10

B．709.99

C．6300.00

D．709.38