It is not easy ____ the answer to the difficult math problem.

A. to have had time B. having time

C. to have time D. to having time

A. not to say B. saying not C. to say not D. not saying

A. laughing at B. to be laughed at

C. being laughed at D. laughed at

A. losing B. to lose C. lost D. your life to lose

A. being heard B. hearing C. to hear D. having been heard

A. sending B. be sent C. being sent D. send

A. playing, doing B. playing, to do C. to play, doing D. to play, to do

A. taking place B. to take place C. holding D. to hold

A. keep you waiting B. having kept you waiting

C. waiting for you D. keep you wait

A. I asking B. my asking C. me to ask D. mine to ask