The electromagnetic spectrum covers an enormous range of frequencies and energies.电磁波谱包括极大的频率和能量范围.Television systems, which transmit 30 picture frames per second, must operate on a broad electromagnetic spectrum.每秒传输30幅...
The stowaway masqueraded as a crew member.偷渡者假扮成乘务员.The crew discovered the stowaway about two days into their voyage.船员在开船约两天后发现了那名偷乘者。Airlines took the view that stowaway incidents should not happen.航空公司认为偷乘飞机这样的事是不应该发...