His meager allotment of gas had to be saved for emergencies.他分到的那一点点煤气必须留着急用。For protection against unforeseen emergencies, you insure your house, your furnishings and your car.为了防范不可预见的紧急情况,人们给房子、家具和汽车上保险。The hospital w...
近岸回流的冲力能把游泳的人涌到海里.The pull of the undertow can drag swimmers out to sea.化学物质在系统中不断循环或回流.Chemical constantly circulate or recycle in the system.这种液体就是回流.This liquid is known as the reflux....