小题1:By car.
小题2:Because he felt tired and thirsty.
小题3:B
小题4:I saw many old people still moving on
小题5:无论有多么困难，如果我们坚持，最终会达到目的。
小题1:从第二段的句子：Then I got into my car and drove off to the park.可知作者是乘汽车去的公园：By car.
小题2:从第四段的句子：I felt tired and thirsty. I wanted to give up and have a good rest on the ground. 可知作者是因为又累又渴，所以想停下来：Because he felt tired and thirsty.
小题3:从后面的句子：I must finish 10 rounds before I went to work.可知是确定目标，选B 。
小题4:I saw是主句 many old people still moving on 是从句
小题5:no matter how引导让步状语从句： if引导的是条件状语从句，还有短语in theend最后：翻译成：无论有多么困难，如果我们坚持，最终会达到目的。