如图所示,物体A在拉力F作用下做匀速直线运动,弹簧秤的示数是5N,那么,拉力F为10N,物体A与地面间的摩擦力为()。
A.5N
B.10N
C.15N
D.20N
参考答案:A
给下列粗体字注音,并解释词语。
(1)甬( )道_____________ (2)鸿( )雁_________________
(3)在( )所不惜_____________(4)患( )难与共_____________
(5)不屈不挠( )_____________(6)浮想联翩( )_____________
We can see _____ stars at night if there are no clouds in the sky. [ ]
A. thousand of
B. thousands of
C. a thousand