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Evidencehasbeenputforwardshowingthatastronautsexposedtolongperiodsofweightlessness_quiteseverely.A.haveaffectedB.hadaffectedC.havebeenaffectedD.hadbeenaffected答案是选c,为什那么不用用had而用have
Evidencehasbeenputforwardshowingthatastronautsexposedtolongperiodsofweightlessness_quiteseverely.
A.haveaffected
B.hadaffected
C.havebeenaffected
D.hadbeenaffected
答案是选c,为什那么不用用had而用have
1回答
2020-04-10 19:28