负数a和它的相反数的差是（ ） A．2a B．0 C．-2a D．a-1a

An instruction is made up of (41) that specify the function to be performed and operands that represent the data to be operated on. For example, if an instruction is to perform the operation of (42) two numbers, it must know (43) the two numbers are. The processor’s job is to (44) instructions and operands from memory and to perform each operation. Having done that, it signals (45) to send it next instruction.

A．data

B．address

C．register

D．operations

部分一次性使用的医疗器械、器具消毒灭菌后可以重复使用。

永磁材料取向成型模具系统中，必须采用磁绝缘材料的零件是（）

基层协会在宣传教育中，动用多种方法帮助群众明白实行计划生育即利国利民，又（）的道理。

A、发家致富

B、利家利已

C、家喻户晓

预膜时水的浊度升高，会使金属表面沉积物增多，从而使腐蚀率相应降低。