问题补充：
This afternoon I was having a PE lesson while I fell down and hurt my foot. I was in greatly pain at that moment, but I tried to act as if nothing has happened until the class was over. Though I had difficulty walk back to my classroom, I still didn’t tell anyone but even refused the offer of help of my classmates. As result, the hurt in my foot became bad. Now I know I am wrong. We can tell others our need for help and accept his help. Some day we can help others in return for. In this way, we can get along to each other happily and peacefully.while → when
答案：
(答案→)while → when
解析：【小题1】when 既可以与延续性动词连用也可以与非延续性动词连用，而while只能与延续性动词连用，故此处while → when
【小题2】形容词修饰名词，副词修饰动词，此处用形容词修饰名词，故greatly → great
【小题3】事情发生在过去的过去，句子用过去完成时，故has → had
【小题4】have difficulty (in) doing sth 在做某事方面有困难，故walk → walking
【小题5】我没有告诉别人，并且不需要我同学的帮助，表示顺承关系，故but → and
【小题6】as a result 结果，固定短语，故result前加a
【小题7】根据语境，应该是情况变得更糟了，故bad → worse
【小题8】前文讲到others 表示很多人，故此处应该将his → their
【小题9】将来的某一天，我们能够作为回报也去帮助他们，in return作为回报，故return后去掉for
【小题10】get along with sb 与某人相处，固定短语，故to → with
