组合音响中红外遥控器都要以（）为中心构成红外遥感系统。
参考答案：微处理器（电脑）
颅底角是_________与_________所形成的角度。
— Do you think the weather will be all right this golden week?
— No, _____ we're lucky, it is reported that there will be sandstorms anyway. [ ]
A. if
B. though
C. unless
D. as
