1.A.for B.with C.on D.as 　　2.A.stars B.sun C.earth D.space 　　3.A.with B.from C.under D.for 　　4.A.use B.live C.eat D.get 　　5.A.again B.also C.besides D.too 　　6.A.environment B.space C.atmosphere D.earth 　　7.A.across B.to C.from D.through 　　8.A.valid B.enormous C.various D.proper 　　9.A.As soon as B.As well as C.As much as D.As possible as 　　10.A.shown B.exposed C.faced D.covered 　　11.A.but B.because C.so D.so that 　　12.A.get B.make C.have D.do 　　13.A.earth B.atmosphere C.space D.environment 　　14.A.pieces B.units C.parts D.elements 　　15.A.receive B.accept C.bring D.catch 　　16.A.conventional B.commonC.general D.normal 　　17.A.shifts B.converts C.modifies D.varies 　　18.A.what B.which C.that D.why 　　19.A.put up with B.keep up with C.come up with D.catch up with 　　20.A.from B.than C.as D.away