(2013·吉林四校高三一诊)I really don't know how to thank you, but for your help, I ________ my lost necklace.

A．couldn't have found

B．mustn't have found

C．couldn't find

D．wouldn't find

桥式吊车上采用双联滑轮组，其特点是不会产生水平位移，滑轮数量（），省力倍数越大。