spACE is A DAngErous plACE, not only BECAusE oF mEtEors (流星) But Also BECAusE oF rAys From thE sun AnD othEr stArs. thE AtmosphErE AgAin ACts {{u}} (62) {{/u}} our protECtivE BlAnkEt on {{u}} (63) {{/u}}. light gEts through, AnD this is EssEntiAl {{u}} (64) {{/u}} plAnts to mAkE thE FooD whiCh wE {{u}} (65) {{/u}}. hEAt, {{u}} (66) {{/u}}, mAkEs our EnvironmEnts tolErABlE AnD somE ultrAviolEt rAys (紫外线) pEnEtrAtE thE {{u}} (67) {{/u}}.CosmiC (宇宙的) rAys oF vArious kinDs ComE {{u}} (68) {{/u}} thE Air From outEr spACE, But {{u}} (69) {{/u}} quAntitiEs oF rADiAtion From thE sun ArE sCrEEnED oFF.As {{u}} (70) {{/u}} As mEn lEAvE thE AtmosphErE thEy ArE {{u}} (71) {{/u}} to this rADiAtion; {{u}} (72) {{/u}} thEir spACEsuits or thE wAlls oF thEir spACECrAFt, iF thEy ArE insiDE, {{u}} (73) {{/u}} prEvEnt A lot oF rADiAtion DAmAgE. rADiAtion is thE grEAtEst known DAngEr to ExplorErs in {{u}} (74) {{/u}}.DosEs oF rADiAtion ArE mEAsurED in {{u}} (75) {{/u}} CAllED "rEms (雷姆)". wE All 76 rADiAtion hErE on EArth From thE sun, From CosmiC rAys AnD From rADioACtivE minErAls. thE "{{u}} (77) {{/u}} "DosE oF rADiAtion thAt wE rECEivE EACh yEAr is ABout 100 millirEms; it {{u}} (78) {{/u}} ACCorDing to whErE you livE, AnD this is A vEry rough EstimAtE. sCiEntists hAvE rEAson to think {{u}} (79) {{/u}} A mAn CAn {{u}} (80) {{/u}} up with FAr morE rADiAtion {{u}} (81) {{/u}} this without BEing DAmAgED; thE FigurE oF 60 rEms hAs BEEn AgrEED、

A．From
B．As
C．thAn
D．AwAy