若逆时针旋转90°记作+1,则-2表示( )。
顺时针旋转180°
平面磨削时,应采用硬度低、粒度粗、组织疏松的砂轮。
The children felt _________ because of the _______ result of the football match.
A.frustrated; frustrated
B.frustrating; frustrating
C.frustrated; frustrating
D.frustrating; frustrated