调节阀的流量特性主要取决于阀芯的形状。
A. 对
B. 错
Listen and choose the best answer.
A. 40.
B. 57.
C. 05.
D. 10.
Listen and choose the best answer.
A. 8400m.
B. 8900m.
C. 8100m.
D. 6300m.
Listen and choose the best answer.
At 6000m or above.
B. At 6000m or below.
C. At 6600m or above.
D. At 7500 or below