梁场存梁养护时间一般不低于（）天。

先阅读短文，再在其后空白处写出各单词的正确形式。单词的第一个字母已给出。

In 1993, Greg Mortenson took a trip to Pakistan to climb K2, the second tallest mountain in the world. On his way down the mountain, he got l (小题1:). Food and water were hard to find, but Mr. Mortenson found a small village. The people there saw that he was in n (小题2:) and helped him.  While in the village, Mr. Mortenson w(小题3:) the children write in the dirt for their school l(小题4:)．The village did not have money to build a school or pay for a t(小题5:)，Before he left, Mr.， Mortenson volunteered to r(小题6:) to the village and help them build a school

Mr. Mortenson went back to the US and wrote to many rich people. He asked them to d (小题7:) money to build a bridge and a school for the village. The I (小题8:) did not work very well, but at last e (小题9:) people heard about Mr. Mortenson’s plan and helped him. That was the beginning of the Central Asia Institute, an organization that has succeeded in building or helping to build more than 130 schools in small villages in Pakistan and Afghanistan With the help of journalist David Relin, Mr. Mortenson wrote the famous book Three Cups of Tea. It is about his work with villages in Pakistan and Afghanistan. Some people have criticized him, however, Mr. Mortenson was given a p(小题10:) in 2009 by the government of Pakistan for his work in the country.

下列哪项不属于传染源（）

A.传染病患者

B.隐性感染者

C.蚊子

D.病原携带者

E.受感染的动物

在一些影视剧和晚会的舞台上，我们常看到烟雾缭绕，创设出了非常好的效果，这其实都是干冰的功劳，干冰是一种极易______（填物态变化的名称）的物质，所以干冰还用来人工降雨，请简述人工降雨的原理______．

用绳AC和BC吊起一重物处于静止状态，如图所示。若AC能承受的最大拉力为150 N，BC能承受的最大拉力为105 N，那么，下列正确的说法是

A．当重物的重力为150 N时，AC、BC都不断，AC拉力比BC拉力大

B．当重物的重力为150 N时，AC、BC都不断，AC拉力比BC拉力小

C．当重物的重力为175 N时，AC不断，BC刚好断

D．当重物的重力为200 N时，AC断，BC也断

（）是指对有关的文献进行研究，在此基础上，对文献中的某些事实、观点、方法和结论加以评价、论述。