在直角三角形ABC 中,∠C= 90°,BC= 12,AC=9,则AB=﹙ ﹚
15
His speech in English was difficult__________.
A in following B for being followed C to follow D to be followed by
气动调节器的缺点是()。
A、易堵
B、易漏
C、易有摩擦阻力
D、以上全部