I have to see the doctor because I________a lot lately．

      A．cough                                           B．coughed         

       C．have been coughing                            D．had coughed

 ______ surprised the family most was ________the girl played basketball very well．

       A．That; that             B．That; what          C．What; that        D．What; what

 Every possible means _______to prevent the air pollution, but the sky is still not clear．

       A．are being used                                 B．have been used                      

       C．has been used                                D．had been used

 _______environmental damage is done, it takes many years for the ecosystem to recover．

       A．Even if                B．If only                 C．While                  D．Once

 Look! The dictionary, ________cover is red, is a birthday gift given by Tom．

       A．which              B．whose              C．its                  D．where

 —Must I give the pen to the manager ?

—No, you may give it to________you think is on duty in the office ．

       A．whomever                                    B．no matter who 

      C．whoever                                     D．who

 Only by shouting at the top of his voice__________．

       A．he was able to make himself hear       

       B．he was able to make himself heard

       C．was he able to make himself hear         

       D．was he able to make himself heard

 — I’d better__________ now．The water is boiling in the kitchen．

   — Good-bye．

       A．ring off            B．ring up            C．ring in               D．ring back

 _______from the top of the tower, the north foot of the mountain is a sea of flowers．

     A．Seeing                                      B．Having seen                        

       C．Seen                                          D．To see

 — Catherine, I have cleaned the room for you．

— Thanks, but you ________it．I could manage it myself．

       A．needn’t do                                   B．needn’t have done 

       C．mustn’t do                                    D．shouldn’t have done