1.She has set a new record , that is , the sales of her latest book ___ 500 million .

A. have reached  B. has reached  C. are reaching

D. had reached

解答：这里时态用现在完成时。因为sales是复数，所以用have，不用has。

2.The teacher together with the students ___ discussing Reading Skills that ___ newly published in America .

A. are；were  B. is；were  C. are；was  D. is；was

解答：主句的主语是the teacher ，是单数，所以首先排除掉A，C。从句的主语是Reading Skills ，一本书的名字，是单数，所以谓语用单数。所以选D。

3.Professor Smith , along with his assistants , ___ on the project day and night to meet the deadline .

A. work  B. working  C. is working  D. are working

解答：主语是Professor Smith ，为单数，所以排除A，D。B选项缺少be动词，所以只能选C 。

总结：在英语学习中，复习、领会、牢记错题非常重要。除了平时背诵单词、语句和语法之外，牢记错题是英语学习的精华所在。