某一时刻,身高1.6m的小明在阳光下的影长是0.4m.同一时刻同一地点,测得某旗杆的影长是5m,则该旗杆的高度是 ( )
A:1.25m
B:10m
C:20m
D:8m
They have taught me to work hard.
分式x-1x+2的值为0时,x的值是( )
如图所示,斜面长s高h,用沿斜面方向的推力F,将一个重为G的物体由斜面的底端A匀速推到顶端B.
试证明:滑块受到斜面的摩擦力f=F﹣ hsG.
—What's thirty and fifty?
—It's e____.
I don't know __________ they have passed the exam.