单选题We should make a car

问题补充：

单选题Weshouldmakeacarefulstudyofhis____.A.useful teaching experiencesB.useful teaching experienceC.usefully teaching experiencesD.usefully teaching experience

答案：

B解析experience作“经验”解时，为不可数名词；用作可数名词时，意为“经历”。