- Mach two equals twice the speed of sound.
二马赫相当于声速的二倍。
- "A sweet temper" is a figurative expression, but "sweet coffee" is not.
"甜蜜的性情"是个比喻的说法，而"甜咖啡"则不是。
- The plane is flying at the velocity of sound.
飞机以音速飞行。
- As the velocity in the nozzle throat is sonic, the effect must be transmitted upstream through the boundary layer.
当喷管喉部达到音速时，这种影响一定是通过附面层向上传播而引起的。
