—Did you have trouble ________ the house?
—No, certainly not.
A．to find B．find
C．on finding D．finding
—Did you have trouble ________ the house?
—No, certainly not.
A．to find B．find
C．on finding D．finding
D
have trouble in doing sth. 在做某事情方面有困难，介词 in 可省。