It’s high time that we students even harder at our lessons as the national entrance exami

问题补充：

It’s high time that we students even harder at our lessons as the national entrance examination is coming nearer.

A. work

B. will work

C. worked

D. have to work

答案：

A. work

B. will work

(答案→)C. worked

D. have to work

解析：考查句型：It’s high time that+主语+过去式/should do ，should不能省略。所以选C。