conundrum

n.(答案有双关意义的)谜语, 难题

contrivance, contrive, contrived, control, control tower, controllable, controlled, controller, controlling interest, controversial, controversialist, controversially, controversy, controvert, contumacious, contumaciously, contumacy, contumely, contuse, contusion, conurbation, convalesce, convalescence, convalescent, convection, convector, convene, convener (also convenor), convenience, convenience food, convenient, conveniently, convent, convention, conventional, conventionality, conventionalize, conventionalize, -ise, conventionally, conventions,