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 __1__ our protective blanket on __2__ .Light gets through, and this is essential __3__ plants to make the food which we __4__ .Heat, __5__ , makes our environments tolerable and some ultraviolet rays(紫外线的) penetrate the __6__ .Cosmic(宇宙的) rays of various kinds come __7__ the air from outer space, but __8__ quantities of radiation from the sun are screened off. __9__ men leave the atmosphere they are __10__ to this radiation; __11__ their spacesuits or the walls of their spacecraft, if they are inside, __12__ prevent a lot of radiation damage.Radiation is the greatest known danger to explorers in __13__ .Doses of radiation are measured in __14__ called“rems (雷目)”.We all __15__ radiation here on earth from the sun, from cosmic rays and from radioactive minerals.The“ __16__ ”dose of radiation that we receive each year is about two millirems; it __17__ according toswheresyou live, and this is a very rough estimate.Scientists have reason to think __18__ a man can __19__ far more radiation __20__ without being damaged; the figure of 60 rems has been agreed.- [4 v9 [4 t8 U& n
1.A.for B.with C.on D.as, K0 f: Y* W" q/ v: u+ L
2.A.stars B.sun C.earth D.space
. J7 `. ?+ e) s* N b 3.A.with B.from C.under D.for
" R# A4 O8 p4 U0 ? 4.A.use B.live C.eat D.get
7 E% h3 L+ e2 E9 ~5 } 5.A.again B.also C.besides D.too
& c" y! l' C- r" x) i6 _ 6.A.environment B.space C.atmosphere D.earth
- c! M, I( M* _! Y- {. K6 `2 g' r 7.A.across B.to C.from D.through% u5 T* X* \+ ^9 @4 j1 u" X. J
8.A.valid B.enormous C.various D.proper! |" [% j E: g
9.A.As soon as B.As well as C.As much as D.As possible as
- }. T6 g9 G( ?4 { 10.A.shown B.exposed C.faced D.covered" A: q* q9 h2 I4 m& d1 w7 e) m3 g% Q
11.A.but B.because C.so D.so that
* K1 g. b5 F8 D- x- g 12.A.get B.make C.have D.do' Y' J7 o' H7 S1 _9 c- c8 j2 x& _5 U
13.A.earth B.atmosphere C.space D.environment: \' T, F/ i, Z8 R; }& H5 D, d
14.A.pieces B.units C.parts D.elements2 m, ~/ q) ?8 P: P, [0 a
15.A.receive B.accept C.bring D.catch, }. E5 D5 _* }
16.A.conventional B.commonC.general D.normal0 { U7 o2 S4 ?( R" V) w
17.A.shifts B.converts C.modifies D.varies: l [) k) F# v6 s0 w) j0 u# U
18.A.what B.which C.that D.why; ~/ A _3 r! V- A6 p1 ^: f& L
19.A.put up with B.keep up with C.come up with D.catch up with
) G6 N9 r. O" ~8 \: z 20.A.from B.than C.as D.away
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