The tutor tells the undergraduates that one can acquire ______ in a foreign language through more practice.
【正确答案】 A
【答案解析】解析：句意：导师告诉大学生们一个人可以通过多实践而精通一门外语。proficiency熟练，精通，与in连用。efficiency效率，功效。efficacy效力，效益。frequency频率，周率。