我寄了信, 但留了份影印本存档.I sent the letter, but kept a copy for my files.校长把我校的所有报告都存档保存.The principal keeps all our school reports on file.清点完所定购的每一件东西后，将这份记录存档。Once you've checked off the items you ordered, put this record...
The pricipal objective in designing cyclones is to create a vortex.设计旋风除尘器的主要目的在于造成涡旋运动.Middle - latitude cyclones originate at the popar front.中纬度 地区的气旋发源于极锋.For particulates, the favored devices are inertial impactors,...