将配制的过饱和二水硫酸钙溶液置于密闭的蒸气压力锅中，在135～145℃，0.2～0.

工业的不断发展，逐步提高了人类的生活质量，同时也带来了一系列的环境问题．

（1）化石燃料的大量燃烧，造成大气中的　     　含量不断上升，从而引起温室效应，同时产生的二氧化硫、二氧化氮等污染物溶于雨水，形成　           　．

（2）合成材料的应用和发展，大大方便了人类的生活，但是废弃塑料带来的　       　也很严重，为了解决这个问题，我们可以采取的措施有　                    　（答一条即可）．

采用反压护道是解决软土地基上路堤的( )问题。

A．

强度

B．

沉降

C．

稳定性

评标委员会对投标书进行初评是以( )为依据，确定投标书的有效性。

A．投标文件

B．招标文件

C．招标公告

D．资格预审文件

我国目前应用的乙型肝炎疫苗属于（）

A.减毒活疫苗

B.灭活疫苗

C.亚单位疫苗

D.多价疫苗

E.基因重组疫苗

There was a woman in Detroit, who had two sons. She was worried about them, especially the younger one, Ben, because he was not doing well in school. Boys in his class played jokes on him because he seemed so (21) The mother (22) that she would help her sons to do (23) in school by herself. She told them to go to the Detroit Public Library to (24) a book a week and do a book report for her.
One day, in Ben’s class, the teacher held up a rock and asked (25) anyone knew it. Ben put up his hand and the teacher let him (26) . "Why did Ben raise his hand" all of his (27) whispered (耳语) and wondered. "He (28) said anything. What could he possibly want to say" To their surprise, Ben not only (29) the rock, but also said a lot about it. He (30) other rocks in its group and even knew (31) the teacher had found it. The teacher and the other students were (32) Ben had learned this from doing one of his book (33) .
Later Ben became the (34) student of his class. When he finished high school, he went to Yale University and (34) became one of the best doctors in the United States.

Ⅱ. 完形填空

/Close
阅读下面短文，从短文后各题所给的四个选项(A、B、C和D)中选出一个最佳选项。

A．that

B．if

C．how

D．why