過去將來時
    由“shall或will的過去式should或would+動詞原形”構成。
    表示在過去某一時刻之后將要發(fā)生的動作或情況。 過去將來時態(tài)如果出現在從句中， 則主句謂語動詞通常是是一般過去時。如：
    e.g. We wanted(想要) to know (知道)when the English class would begin(開始).
    過去將來時的否定和疑問結構：
    It would be fine(晴朗的). 天氣會晴朗起來
    It wouldn’t be fine.
    Would it be fine?
    be going to do...
    am/is going to do... →→→→→ was going to do...
    are going to do... →→→→→ were going to
    “be to+動詞原形”
    am/is to do ... →→→→→ was to do...
    are to do... →→→→→ were to do...
    “be about to+動詞原形”
    am/is about to do ... →→→→→ was about to do...
    are about to do... →→→→→ were about to do...
    “be+現在分詞”
    am/is doing ... →→→→→ was doing...
    are doing... →→→→→ were doing...