【题目】Not having a good ________ of English can be a serious barrier to achieving your goals.
A.demand
B.appreciatio
C.command
D.experience

【答案】C
【解析】这题考查固定词组：having a good command of“精通”，句意是：不能精通英语可能是你取得成功的严重的障碍。选C。