The students are reading books quietly in the classroom。

The class are reading in the classroom. reading就是读书，地道的英文一般不用read books.

The students were reading books，when the teacher came in the classroom.希望对你有帮助，有不懂的可以追问！

The students were reading books， when the teacher came in the classroom.希望对你有帮助，有不懂的可以追问！

Three students are reading books in the classroom.

聪明的英语读法是[smɑːt]，单词是smart。一、发音英：[smɑːt]；美：[smɑːrt]二、中文翻译adj.聪明的；机敏的；精明的；光鲜的；衣冠楚楚的；衣着讲究的；整洁而漂亮的；时髦人物的；快速的；智能的 vi.感到剧烈刺痛；（因批评、失败等）难过，烦恼 n.创伤；刺痛；疼痛；...

children are playing football .你妈妈在哪里？她正在厨房里烧饭。where is your mother? she is cooking in the kitchen.你在干什么？我正在写作业.what are you doing ? I am doing my homework.我们正在教室里读书 we are reading in the classroom .纯属手翻，绝对正确。请楼主验收！！！

He is such a smart/clever student. 这里用such起到一定的强调语气。为了强调“smart/clever”，也可以用感叹句：How smart/clever a student he is! = What a smart/clever student he is.我比较喜欢How的那一句。强调句还有一个固定句式是it is...that...但是，我不认为适合用在这里。

我们正在教室里上课，用英语翻译如下: We are having classes in the classroom。表示正在做某事，用be+doing something。We are having English class.我们正在上英语课。动词加ing，如果后面有不发音的e，要去掉r再加ing。

There are a great many students in the classroom.There are a lot of/plenty of students in the classroom.There are a number of students in the classroom.