In the after-class activities the students had plenty ofand gained a lot of practical .A.

问题补充：

In the after-class activities，the students had plenty ofand gained a lot of practical .

A. experience;experiences

B. practices;experience

C. practice;experience

D. exercise;knowledges

答案：

A. experience;experiences

B. practices;experience

(答案→)C. practice;experience

D. exercise;knowledges

解析：practice和knowledge都是不可数名词，排除B、D两项；experience既可作可数名词“经历”，也可作不可数名词“经验”。在此应为“经验”之意，为不可数名词。