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  • Since the mid-1960's considerable research_____in embryo transplants in many countries.

    Since the mid-1960's considerable research_____in embryo transplants in many countries.
    A has carried out
    B was carried out
    C carried out
    D has been carried out
    這個(gè)題的謂語(yǔ)是哪個(gè)呀?
    不對(duì),是這題的主語(yǔ)是哪個(gè)啊
    英語(yǔ)人氣:582 ℃時(shí)間:2020-05-25 12:23:06
    優(yōu)質(zhì)解答
    Dsince..(the mid-1960's) 用于完成時(shí)的時(shí)間狀語(yǔ),表明本句用完成時(shí)主語(yǔ)是considerable research,大量的研究,research研究是抽象名詞不可數(shù),視為單數(shù)概念,因此要用has,還有研究不是自己做的,被做的,因此要用被動(dòng),就是...
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