问题补充：
As a senior high student, you should your energy on how to master the skills of learning.
A. impress
B. spend
C. concentrate
D. use
答案：
A. impress
B. spend
(答案→)C. concentrate
D. use
解析：词的用法。Concentrate ...on ,集中...于spend time/money on sth/in doing sth 花时间/金钱做某事. Impress 给...印象句意：作为一个高中生，你应该把你的精力集中在怎样掌握学习的技能上。故选C
