A,锻炼,不可数名词,习题,可数名词,此处为锻炼·那答案给的B哦（我也选的是A）（智力的）运用；（尤指）锻炼运动时不可数，比如说：The doctor advised him to take more exercise.(发音，体操，保健，深呼吸，钢琴等)练习，训练时可数，比如说： The teacher set her class a mathematics exercise for homework.还有（部队等的）操练，演习也是可数的，比如说：military exercises军事操练哦这样( ⊙ o ⊙ )啊！