用友报表系统中，取数操作一般是通过( )实现的。A．函数B．关键字C．直接输入D．

小陈在观察成熟叶肉细胞的亚显微结构照片后得出如下结论，不正确的是[ ]

A．叶绿体和线粒体都有双层膜

B．核糖体附着在高尔基体上

C．内质网膜与核膜相连

D．液泡是最大的细胞器

短文改错。

Before he was a teacher, Bob told me that what he would like to do a lawyer when he was at school.

He had worked very hard at his lessons and try to enter into a famous university, but something unhappy

happened to his family, which made necessary for him to work for a life. As a young man, he had been a

bus-driver, a dust-man , a salesman. But he spent his spare times studying and finally became a college

teacher. "Young people," he often said, "full of wishes and hopes after they step into society."

在人机系统中，信息在信息源和信宿之间传递有三种模式（），（），（）。

普通制桶焊缝烘干机传送带是靠（）降温的。

A、压缩空气吹

B、自然风冷

C、鼓风机吹

D、循环冷却水

正常使用的塔机（）都应对制动器进行检查。