No matter how frequently __________, the works of Beethoven still attract people all over the world.
| A．performed | B．performing |
| C．to be performed | D．being performed |
. The missing boys were last seen _______ near the river.
| A．playing | B．to be playing | C．play | D．to play |
. The patient was warned _______ oily food after the operation.
| A．to eat not | B．eating not | C．not to eat | D．not eating |
. I regret _______ you that we are unable to offer you employment.
| A．informing | B．having informed | C．to inform | D．to informing |
. You had better get a doctor _______ your bad tooth.
| A．pull out | B．to pull out | C．pulled out | D．pulling out |
. The matter had better _______ as it is.
| A．leave | B．being left | C．leaving | D．be left |