如图利用弹簧测力计测量金属块B的重力时,使测力计内弹簧伸长的力是( )
A.金属块B的重力
B.绳子A对弹簧的拉力
C.金属块对绳子A的拉力
D.弹簧对金属块B的拉力
答案:B
Gun control is a subject ___ Americans have argued for a long time.
A.of which
B.with which
C.about which
D.into which
半导体静态RAM靠______存储信息,半导体动态RAM靠______来存储信息。