Adam met a doctor who explained the problem. As a result, he stopped taking cocaine.

4 But that's because I was stupid enough to play football in the rain.

　　This is because ...."那时因为..."表语从句表示原因

　　This is why ... "那就是为什么" 表语从句表示结果

　　The reason why ...is /was that

　　Eg. I was late; this is because my bike broke down on the way to school

　　 I was late again; this is why I was criticized by my class teacher.

The reason why I was late was that my bike broke down on the way to school.

5 Two years ago I broke my arm playing football.

　　Playing football 现在分词短语作状语，逻辑主语是整个句子的主语。

　　现在分词做状语的几种情况：

　　1）表示时间可以转换成时间状语从句。从句引导词也可以保留

　　Looking out of the window, I saw groups of students passing by the classroom .

　　Working in the field, the peasants talked and laughed merrily.

　　While working in the factory, I learned a lot from the workers.

　　While reading the book, he nodded from time to time .

　　2）表示原因可以转换成原因状语从句

　　Being a student ,I must study hard.

　　Not knowing what to do ,he came to me for help .

　　3）表示伴随，方式，补充说明和结果，可改写为并列句

　　He came running back to tell us the news.

　　She stood there waiting for the bus .

　　Laughing and talking , the students went out of the classroom.

　　The child fell, striking his head against the door .

　　She set out soon after dark , arriving home an hour later.

6 I'm captain of the class team at school and I'm also a member of the Senior High team.

　　表示独一无二的官衔，职位的名词在做以下成份时，前面常不要冠词。

　　1)作补足语。

　 In 1864,Lincoln was elected President of the U.S.A. for the second time.(主补)

They made him monitor.（宾补）