It could have saved me some trouble （） about it.
A: had I known
B: I had known
C: did I know
D: I knew
A: had I known
B: I had known
C: did I know
D: I knew
举一反三
- ______, I would have phoned you. A: If I knew it B: Had I known it C: If I know it D: Did I know it
- So little（）about the topic that I had nothing to talk about. A: will I knew B: did I know C: do I know D: have I known
- ______ the result, I would not have asked you to tell me. A: If I know B: Had I known C: I had known D: If I knew
- Little _____ about him when I first met him in that company. A: have I known B: had I known C: do I know D: did I know
- ( )he was seriously ill, I would not have told him the truth A: If I knew B: If I know C: Had I known D: Did I know