77. Noah Webster an American Dictionary of the English Language in two volumes in 1828, and since then it ____ the recognised authority for usage in the United States. 

A. published/became​B. has published/has become 

C. published/was becoming ​D. published/has become 

78. She ____ of great help to us because she ____ for such a long time with us. 

A. has been/had lived​B. has been/has been living ​C. has been/lived​D. was/has lived 

79. I ____ the book yet so I can't tell you what happens. 

A. haven't finished​B. haven't been finishing ​C. didn't finish​D. hadn't finished 

80. Peter has been a junior clerk for three years. Lately he ____ for a better post but so far he ____ anything. 

A. looks/hasn't found​B. have looked/haven't found 

C. has been looking/hasn't found​D. has looked/hasn't found