Unit 4 Earthquakes语篇演练十九.docx

Unit4Earthquakes语篇演练(十九)
时间安排：第七周·周一演练题型：阅读理解＋完成句子建议用时：25分钟
答案栏：1～4____________
Ⅰ.阅读理解
Whentheylookatthesky,peopleusuallyfindtheskylooksblue—notorange,red,greenoryellow.Doyouknowwhy?
Unlikethemoon,theearthissurroundedbyanatmosphere.Theatmosphereisamixtureofgasses,mostlynitrogenandoxygen.Thewaythesunlighttravelsthroughtheatmospheremakestheskycolored.
Whyblue?Itdoesn'tlooklikeit,butlightismadeupofseveraldifferentcolours,likeyouseeinarainbow.Eachofthesecolourstravelsinawave,butthewavelength(distancebetweenthetopsofeachwave)varies.Redlighthasalongwavelength,whilebluelighthasamuchshorterwavelength.Whenlightfromthesunentersouratmosphere,thewavescollide(碰撞)withgasmolecules(分子).Thelongerwavelengths,likeredandyellow,passstraightthroughandappeartousas“regular”sunlight.Shorterwavelengths,likeblue,bumpintothegasmoleculesandscatterindifferentdirections.Someofitstillmakesitthroughdirectly,buttherestisreflectedbacktooureyesfromalldirections,sothewholeskylooksblue.
Theskyusuallylookslightblue.Butitwouldbedarkblueifyoustoodontopofthehighestmountain,wherethereislessairtoscatterthesunlight.
Sometimestheskydoesn'tlookblue.Atsunriseandsunset,thelightfromthesunsometimesscatteredinsomewaythatyouseered,orange,andothercoloursinthesky.
1．Whydoestheskylookblue?
A．Thesunlightisblueitself.
B．Thesunlightismadeupofallthecoloursthesameasarainbow.
C．Thebluelightisscatteredmostamongallthelights.
D．Thesunlightcontainsonlythebluelight.
2．Accordingtothepassagetheskytheastronaut(宇航员)seeswouldbe________.
A．lightblue B．deepgreen
C．darkblue D．redororange
3．Whencanyouseetheskybecomeredororange?
A．Inthemorning.
B．Inthesunshine.
C．Whenyoustandonthetopofamountain.
D．Whenyouareinspace.
4．WhichofthefollowingisNOTtrue?
A．Whenyoustandonthepeakofthehighestmountaintheskylookslightblue.
B．Weusuallyjustseethebluelightwhenthesunlightpassesthroughtheair.
C．Theskylooksorangeindusk(黄昏)．
D．Theredlightisscatteredlessthanthebluelight.
Ⅱ.完成句子
1．Theclassroom________________________willsoongetrepaired.(break)
窗户全破了的那间教室会马上得到修缮。