1.as  soon  as…一…就…=directly/immediately/instantly…

 　　=the  second  /  theminute  /  themoment  /  theinstant…

　　Eg.He  came  around  to  see  me  as soon  as  /  the  moment  /  immediately   he   checked   in  the  hotel.

　　他刚一入住宾馆就来看我.

　　Theyinformedusthenewsimmediately/directlytheygotit.

　　他们一得到消息就通知了我们.

　　Thepolicemancametothespotthemoment/theinstant/theminutesheheardoftheaccident.一听说事故，这位警察就到了现场.

　　2.….before….

　　(1).没来得及…就…

　　Therooffellbeforehehadtimetodashintotheroomtosavehisbaby.

　　他还没有来得及冲进房间把孩子就出来，房顶就塌了.

　　HeranoffbeforeIcouldstophim.

　　Tomygreatdisappointment，myfavoritesingerlefttheconcertbeforeIcouldhaveawordwithhim.

　　(2).过了多久才怎么样，动作进行到什么程度才怎样

　　Theywalkedaboutthirtymilestothewestbeforetheysawavillage.

　　Theyworkeddayandnightaboutthreedaysbeforeeverythingreturnedtonormal.

　　ThreeyearspassedbeforeIknewit.

　　3.Itwas+时间段+before….过了多久才….；

　　Itwasnotlongbefore…不久就…

　　Itwill(not)be+时间段+before…要过多久(不久)…..才…..

　　Eg.Itwasnotlongbeforehesensedthedangeroftheposition.

　　Itwasthreeyearsbeforehecameback.

　　Itwillbehalfayearbeforeyougraduatefromthisschool.

　　4.nosooner…than…=hardly…when…一…就….，刚刚…就…

　　Nosooner/hardly+过去完成时，than/when+一般过去时

　　如果nosooner，hardly位于句首，主句要倒装.

　　HehadhardlysatdowntohavearestwhenthedoorbellrangandincameAllan.

　　Nosoonerhadhegotoffthetrainthanhisdaughterrantowardshim.

　　Hardlyhadwearrivedwhenshestartedcryingtogohome.

　　5.once一旦….，表示时间和条件

　　Onceyouunderstandthisrule，youwillhavenofurtherdifficulty.

　　Onceyouhavedecidedtodosomething，youshoulddoitwell.

　　Onceyouenterthechemistrylab，youshouldfollowtheteacher’sinstructions.