Hypersonic wind tunnels operating at very low densities were developed starting in about 1960.低密度超音速风洞大约开始发展于1960年.It would reach hypersonic speeds -- five times the speed of sound.也就是说,要使飞机达到特超音速—即音速的五倍.FEM FCT is used ...
虽然重拍了好几次，导演罗恩·霍华德仍然对妮科尔的表现不满意。The director, Ron Howard, was dissatisfied with Nicole's response even after several retakes.这些照片不够清晰, 你最好得重拍.These photographs lack definition. You'd better have them taken again....