这是七年级上册英语的重点

He is interested in singing. = He is keen on singing.

They are interested in dancing. = They are keen on dancing.

doing---表示动词的现在分词（-ing形式）；即在这个短语中，动词必须用现在分词。 动词变为ing形式分几大类，具体分类第二单元语法课件里有详细讲解。

I am interested in playing basketball. = I am keen on playing basketball.

Are you interested in playing the piano? --- No, I am not.

钢琴属于西洋乐器，所以在play后面要加the；而球类运动（如basketball等）则不用

对某物感兴趣；热衷于某物

Fred is interested in sports. = Fred is keen on sports.

Our teachers are interested in music. = Our teachers are keen on music.

当需要表达的意思是对某物体感兴趣时，不需要加动词，直接加名词或名词短语即可。

She comes from China. = She is from China.

主语是第三人称单数，动词后要加s；句中有be动词时，要用is（过去时用was） She doesn’t come from China. = She is not from China.

变为否定句时，要注意句中是否有be动词：

有be动词时，直接在be动词后加not；

没有be动词时，则需添加一个助动词（do / does），然后在助动词后加not.

Does she come from China? = Is she from China?

变为疑问句时，句子中如果有be动词，就将be动词提到主语前，句尾加问号；

如果没有be动词，则需添加助动词（do / does）并放到句首，同时，句中的动词必须变为原形。（comes come）

This movie was based on a real story.

= This movie was from a real story.

= This movie came from a real story.

这部电影是根据一个真实故事改编的。（这部电影来自一个真实的故事）

be based on...意思是“以...为基础”；

在例句的这种情况中，可以用be from和come from来替换。（其它时候不可以替换） 电影的改编过程，通常都是已经完成的事情，所以大多用过去式。

be动词的过去式为was, were；动词过去式大部分直接加ed，但也有少数特殊变化。 Was this movie based on a real story?

= Was this movie from a real story? = Did this movie come from a real story?

变为疑问句时，特别要注意动词的时态；动词过去式决定助动词必须用did.