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在意义方向，或是指未来时，其事之实现可能较第一类为小（假设性较重），或是指现在时，则显然与目前事实不符。在形式上，前半句式用过去时，或用should（不用would）etc.，后半句式用过去未来式（should，would，could，etc.）；或用未来式。
If I had the book now, I would let you have it. （但是我现在没有这本书）
If I had the book on Monday,I would let you have it.
If I should have the book on Monday, I would let you have it.（但是星期一未必能把这本书找来）