Itis+時間段+since…

“自從...以來有一段時間了”。

Itis+時間點+when…

“當……時候時間是……”。

Itis+時間段+before…

“在……之前有一段時間”。1/9Itwaspastoneo’clockwhenhecamein.Itwon’tbelongbeforetheyunderstandeachother.Itwaslongbeforeshecameback.Itwillbelongbeforewemeetagain.Itwillbefiveyearsbeforehemeetsyouagain.Itis/hasbeenfourdayssinceIcaughtacold.Itis/hasbeentwoweekssincewemetlast.2/9他哥哥入伍三年了。他哥哥退伍三年了.他病了兩星期了。他病愈兩星期了。他們結婚到現(xiàn)在已經十年了。他到這兒已經二十分鐘了。。3/9很快后我們就能做好旅行準備工作了。三年以后我們才能再次相見。一個小時以后他才完成了工作。他完成工作（到現(xiàn)在）已經一個小時了。他在這兒待了約有十分鐘。4/9練一練：

1.Hewentabroadin1997andhasnevercomeback.Itiselevenyearssincehe____thecompanyathome.A.takeschargeofB.tookchargeofC.isinchargeofD.wasinchargeof

2.Theyaskedmetohaveadrinkwiththem.IsaiditwasnineyearssinceI______agooddrink.A.enjoyedB.wasenjoyingC.hadenjoyedD.hadbeenenjoying

5/93.Itwasaboutmidnight_________wefoundthelostchild,cryingunderatree.A.thatB.untilC.whenD.where4.Itwassixdaysago_________Ispoketoyouaboutthismatter.A.thatB.unlessC.sinceD.until6/95.Itwasten_________hestoodataunt’sdoorandrangthebell.A.whenB.untilC.sinceD.that6.Ithinkitwon’tbelong_________theyunderstandeachother.A.whenB.untilC.sinceD.before7/97.Itwasevening____wereachedthelittletownofWinchester.(天津卷)A.thatB.untilC.sinceD.before8.---DidJackcomebackearlylastnight?---Yes.Itwasnotyeteighto’clock________hearrive