I'm very glad to see you here.I()you had come already.A.don't B.haven't C.didn't knowD.hadn't know

I'm very glad to see you here.I()you had come already.A.don't B.haven't C.didn't know
D.hadn't know

从宾语从句you had come already的时态来看主句时态应与从句时态保持一致,故排除A和B.
联系上句,意为很高兴在这里见到我,我都不知道你已经来了.其中“我都不知道”是现在不知道,而hadn't是过去完成时态,显然不符合,故排除D

因为already是现在完成时的标志词之一