In out-of-class activities, the students had plenty of ________ and gained a lot of practical(实用的)________．
A.experience; experiencesB.practices; experienceC.practice; experienceD.exercise; knowledge在线课程C
practice“锻炼”，是不可数名词；experience当“经验”讲时是不可数名词，当“经历”讲时是可数名词，在本句的意思是“经验”。故选择C项。