How long does it you to get to the museum by bus? [ ]
A. get
B. take
C. cost
答案:B
已知a与b互为倒数,c与d互为相反数,且|x|=3,则|-3ab|-(c+d)+2x=______.
TC型磁力控制盘由哪些主要电器元件组成?各自有哪些功能?