A:6
B:5
C:4
D:3
把一副三角板如图甲放置,其中 ∠ACB=∠DEC=90∘ , ∠A=45∘,∠D=30∘ ,斜边AB=6cm,DC=7cm把三角板DCE绕点C顺时针旋转15°得到△D1CE1(如图乙).这时AB与CD1相交于点O,与D1E1相交于点F.
下列现象中,由动能转化为重力势能的是( )
She is ____ (good) than Alice at swimming.
— How are you feeling here?
—It's quite hot. I don't know _____ to go or stay.
同我国隔海相望的国家从北到南依次是( )