In order to meet the deadline Professor Smith along with his assistantsthe project day an

问题补充：

In order to meet the deadline, Professor Smith along with his assistantsthe project day and night.

A. work on

B. works at

C. is working on

D. are working on

答案：

A. work on

B. works at

(答案→)C. is working on

D. are working on

解析：考查词组和主谓一致。A. work on从事，忙于，B. works at致力于，因为主语由along with,连接时，其谓语动词的单复数形式通常由前面的词来决定。就是Professor Smith故用单数谓语，在BC里面选择，句意：为了如期完成，斯密斯教授和他的助手日夜忙着这个项目。答案为C项。