第31题: [单项选择]The main function of piston compression rings is to () A. prevent excessive cylinder liner wear B. reduce friction losses in the engine C. seal the space between the piston and the liner D. limit upward flow of lube oil into the combustion space 参考答案:C
第34题: [单项选择]In C language, ______ are used to create variables and are grouped at the top of a program block. A. declarations B. dimensions C. comments D. descriptions 参考答案:A 答案解析:[解析] 译文的含义是:在C语言中,( )用于创建变量,而且在程序块顶端分组。
选项A、B、C、D的含义分别是声明、维、注释、描述。选项A符合题意,为所选。