Question

Up to now, they _________ a good way to solve that problem. A．didn’t find B．can’t find C

Up to now, they _________ a good way to solve that problem. A．didn’t find B．can’t find C．hadn’t found D．haven’t found

Answer 1

D

考查时态。Up to now，到现在为止，是现在完成时态的标志，所以选D。