77. By the end of this year, Tom ________ English for three years.

A. has studied            B. will be studying            C. will have studied      D. has been studying

78. In 2014 a robot named Philae, part of the Rosetta mission, ______ landed on a comet.

A. success              B. successfully          C. successful               D. unsuccessful

79. Mai is really good at English. She practices _______ English every day.

A. speak                     B. to speak                             C. speaking                           D. spoke

80. Jane: ‘Why don’t we have a look round the campus?’

    Mary: ‘_________________’

A. Yes, why not?                  B. Yes, thanks                       C. It’s my pleasure    D. Do we?   

81. My house was very dirty because I ______ it for weeks.

A. hadn’t cleaned            B. didn’t clean             C. haven’t cleaned            D. don’t clean

82. Lan spoke English ______ after she lived in England for several months.

A. nature                    B. natural                                           C. naturally                           D. unnaturally 

83. She spent the whole day ______ in her office, so she came home exhausted.

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