Before leaving the classroom ,please turn off the lights.的意思?

please make sure youPlease make sure you _________ the door before leaving the room.A.lock B.will lock C.should lock D.must lock选什么？为什么？ do not forget to turn off the lights before leaving the room 为什么是leaving 不是leave before leaving the room,he turned off the radio.这里为什么要用动名词leaving,而不是其原形? 英语翻译We___very early so we packed the night before.(顺带翻译一下)A.leave B.had left C.were leaving D.have left 7.We __very early so we packed the night before.A.leave B.had left C.were leaving D.have left求翻译 did you leave the park early yesterday afternoon?no,I__there___it was closed.A left;before B stayed;until C was staying;after D was leaving;until Before leaving the laboratory,guaranteed that the lamp and the window have closed Before leaving the laboratory, guaranteed that the lamp and the window have closed 是什么意思? Customers are asked to make sure that they ​______ the right change before leaving the shop.Customers are asked to make sure that they ______ the right change before leaving the shop.A.will give B.have been given C.have given D.will be given 英语翻译Necessary ,the manager ,finish the whole task ,before leaving for a holiday. Before leaving the classroom ,please turn off the lights.的意思? before you leave?turn in the paper before leaving我想问的是 如果在before 后面加个you 还是 before you leaving吗?还是before you leave Before leaving for the airport I have enough time to do something为什么live家ing? Lucy usually enjoys _____(she) in front of the mirror before leaving home. keep your windows closed before leaving the room.为什么用“closed”而不用“closing? lucy usually enjoys herself in front of the mirror before leaving leave before 7 o’clock,or you will miss the train.为什么用leave?不用leaving? Before leaving the train,make sure you take all your bags with you的意思?