下列影响玉米生存的生物因素是 A．空气 B．老鼠 C．水分 D．温度

When I was at university, I studied very hard. But a lot of my friends did very l    work. Some just did enough to pass the exams. Others didn’t do quite enough. Fred Braines was such a student. He spent more time drinking in the T   House than working in the library.

Once at the end of the term, we had to take an important test in Chinese. The test had 100 questions. Beside each question we had to write “True” or “False”. While I was studying in my room, Fred was watching TV. Fred usually worried a lot the night before a test. But on that night he looked very e   . Then he told me of his idea.

“It’s very simple. There are 100 questions and I have to get 50 right to pass the test. I will take a coin into the examination room. I haven’t studied a Chinese book for months, so I will toss (抛) the coin. In this way, I’m sure I’ll get h    of the questions right.”

The next day, Fred came happily into the examination room. As he sat tossing a coin for half an hour, he wrote down his answers. Then he left, half an hour b    the rest of us.

The next day, Fred met his Chinese teacher at the school gate. “Oh, good,” he said. “I am sure you have got the r    of the test. Did I pass the test? ”

The teacher looked at him and smiled, “Ah, it’s you, Braines. Just a minute. ” Then the teacher reached his pocket and took out a coin. He threw it into the air, caught in his hand and looked at it. “I am sorry, Braines, you f   ! ”

肝藏血与脾统血的共同生理功能是（）

A.贮藏血液

B.调节血量

C.统摄血液

D.防止出血

E.化生血液

按国发【1982】62号文件规定享受的“生活补贴”应如何发放？

最简单的交换排序方法是( )。

A．快速排序

B．选择排序

C．堆排序

D．冒泡排序

冬季起放井架时，要特别注意检查各气控部分有无（），防止（）而造成事故。