How often do you exercise? 你多久去锻炼一次？ 句中的 “exercise”是动词，意思是“锻炼”。“how often”：常用来询问做事的频率。“多久…一次” 回答通常是: “（多久）一次” 或“一天/周/月/年(多少)次”。 例如：How often do you have a composition? 你们多久写一次作文？ We write a composition once a week. 我们每周写一次作文。
… next week is quite full for me. 下周我的时间都安排满了。
How come? 怎么会这样呢？
I have dance and piano lessons. 我上舞蹈和钢琴课。
But do you want to come? 你想去吗？ 在正式的英语中邀请人一起去时，常用come而不是go。
Twice a week. 一周两次。 注意英语关于“次数”的表达方式：once 一次, twice两次, three times三次, four times 四次. 也就是说，记住“once 一次, twice两次”的表达方式，三次以上用“基数词 + times”。表达：“多久…次”用“次数 + 时间”如：once a week 一周一次；twice a month 一月两次; five times a year 一年五次。
She says it's good for my health. 他说（喝牛奶）对我的健康有好处。 be good / bad for 对…有好处/坏处。
Here are the results. 这里是结果。本句是个倒装句，主语是“the results: 结果”。 因此，谓语动词用were。 high school: 高中，初中是 middle school。
Forty-five percent exercise four to six times a week. 百分之四十五的（学生）每周锻炼四至六次。I will stay here for one or two days. 我在这里呆一两天。
…twenty percent do not exercise at all! 百分之二十的（学生）根本就不锻炼。“not…at all” 根本就不……
The other ten percent use it at least three or four times a week. 其余百分之十的（学生）一周至少上网三至四次。 “the other” 其余的…
The answers to our questions about watching television were also interesting. 对我们关于看电视问题的回答也非常有趣。 “answer to… 对……的回答。 “question about… 对……的提问。
It is good to relax by using the Internet or watching game shows. 通过上网或观看比赛来放松一下是很不错的。 “by”是“靠，通过” 的意思。句中的it是形式主语。真实主语是后面的不定式短语。
But we think the best way to relax is through exercise. 但我们认为放松的最好方式是通过锻炼。 “to relax” 是不定式短语作定语，修饰the best way.
Exercise such as playing sports is fun. 像运动这样的锻炼是很有趣的事。 “such as” 常用来举例，意思是“像…...的……”， 注意, fun 前边不用冠词。
It is healthy for the mind and the body. 这有益于身心健康。
重点句子归纳：
How often do you exercise?
We found that only fifteen percent of our students exercise every day.
We were surprised that ninety percent of them use the Internet every day.
We think the best way to relax is through exercise.
It is healthy for the mind and the body.
It is good to relax by using the Internet or watching game shows.
单元语法点讲解
How often名 词 How often 常用来询问做事的频率。 意思是“多久…一次”， 回答通常是: “（多久）一次” 或“一天/周/月/年(多少)次”。 表示次数的词有：“once(一次)，twice(两次)，three times(三次)，four times（四次）。也就是说，三次以上用“基数词 + times”。表达：“多久…次”，用“次数 + 时间”如：once a week 一周一次；twice a month 一月两次; five times a year 一年五次。
频度副词 用来表示做事的频率。英语中常用的频度副词有：always总是, usually通常, often常常, sometimes有时, seldom很少, never从不.
国外英语书用英语对频度副词解释是：always(all of the time), usually(most of the time), often(much of the time), sometimes(some of the time), seldom(almost never), never(not at any time).
有的书把这几个词数字化，具体表示是：always 100%, usually 90%, often 60%, sometimes 30%, seldom 2%, never 0%
课堂在线小测验
一、课文理解检测
Last month we asked our students their free time activities. Our questions were exercise, use of the Internet and watching TV. Here the results.
We found that only fifteen percent of our students exercise day. Many students often go . The answers our questions about watching television also interesting. Only two percent fo the students watch TV one to three times week. It is good to relax using the Internet or watching game shows, but we think the best way relax is through exercise.
参考答案：
about, about, are, every, online, to, were, a, by, to.
