DirECtions: thErE ArE 10 BlAnks in thE Following pAssAgE. For EACh numBErED BlAnk, thErE ArE 4 ChoiCEs mArkEDA,B,C、AnDD、

thE kEy to thE inDustriAlizAtion oF spACE is thE u.s. spACE shuttlE. {{u}} (51) {{/u}} it, AstronAuts will ACquirE A workhousE vEhiClE {{u}} (52) {{/u}} oF Flying into spACE AnD rEturning mAny timEs. {{u}} (53) {{/u}} By rEusABlE roCkEts thAt CAn liFt A loAD oF 65 000 pounDs, thE shuttlE will CArry DEviCEs For sCiEntiFiC inquiry, As wEll As A vAriEty oF militAry hArDwArE. {{u}} (54) {{/u}} morE signiFiCAntly, it will DElivEr mAtEriAls AnD mAChinEs into spACE For inDustriAl purposEs {{u}} (55) {{/u}} two DECADEs Ago whEn "sputnik" (ArtiFiCiAl sAtEllitE) wAs ADDED to thE voCABulAry. in short, thE {{u}} (56) {{/u}} importAnCE oF thE shuttlE liEs in its promisE As An EConomiC tool. whAt mAkEs thE spACE shuttlE {{u}} (57) {{/u}} is thAt it tAkEs oFF likE A roCkEt But lAnDs likE An Air plAnE. {{u}} (58) {{/u}} whEn it hAs ACComplishED its mission, it CAn BE rEADy For {{u}} (59) {{/u}} trip in ABout two wEEks. thE spACE shuttlE, thE worlD’s First truE spACEship, is A mAgniFiCEnt stEp {{u}} (60) {{/u}} mAking thE impossiBlE possiBlE For thE BEnEFit AnD survivAl oF mAn.

A．sErvED
B．powErED
C．ForCED
D．rEinForCED