(   )1.The students are clever. They have no problems _____ out the math problem.

           A.work                  B.working              C.works                    D.to work

(   )2.—Do you know where Tom is?

           —Yes. He _____ his hometown.

           A.went to               B.goes to                C.has gone to            D.has been to

(   )3.There are many kinds of bikes here. She can’t decide _____.

           A.where to buy       B.which to buy       C.how to go there      D.when to go there