—How do you feel now after the long hiking?
—I'd like nothing but to sleep for _______ more hours!
A:few
B:a few
C:little
D:a little
如图所示,有一质量不计的长木板,左端可绕O点转动,在它的右端放一重为G的物块,并用一竖直向上的力F拉着。当物块向左匀速运动时,在此过程中,拉力F( )