1.i would have come earlier ,but i ___that you were waiting.

　　A.didn't know B.hadn't known C,wouldn't know Dhaven't known

　　2.had she found it ,she ____it

　　A.would have sent B.sent C.should send D.send

　　3.i'd rather that you ___right away

　　A.leave B.left C.should leave D.will leave

　　4.it was a pity that he ____so careless.

　　A.is B.was C.should be D .were

　　1.A 本句是虚拟语气和真实语气的混合，逗号前面那句是虚拟语气，后面那句是真实语气，所以选一般过去时。句意：（我要是早知道你在这等我，）我就来早一些了，但是我并不知道你一直在等我。事实上我并没有来早，但是不知道你在等我是真实的。

　　2.A 逗号前那句其实是if从句，用的是倒装结构，也可以是if she had found it

　　本句是对过去情况的虚拟，从句用过去完成时，主句用would+have done

　　3.A would rather 句后用动词原形表示虚拟

　　4.D it在这里是形式主语，真正的主语是后面的that从句，这也是虚拟语气的一个句型，但是要用过去式表示虚拟,并且be动词一律用were。还有行为动词的比如：It's time you went to bed.