三年级英语语法知识总结 (一)
常考的强调句结构是it 引导的。
It is (was) 被强调部分+ that (who) + 句子其他部分。
此结构强调的成分仅限于主语，宾语和状语。
It is from the sun that we get light and heat.
It was not until I had read your letter that I understood the true state of affairs.
典型例题
1) It was last night ___ I see the comet.
A. the time B. when C. thatD. which
答案C. 强调句的结构是： It +be +强调部分 + that (who) + 主谓句。 强调句的连词只有两个，that和who。当强调的部分是人，且为句子的主语时，才用 "who"，其余用that。
原句： My father did the experiment in the lab yesterday evening.
强调主语： It was my father who did the experiment in the lab yesterday evening.
强调宾语： It was the experiment that my father did in the lab yesterday evening.
强调时间： It was yesterday evening that my father did the experiment in the lab. (注意不用when)
强调地点： It was in the lab that my father did the experiment yesterday evening.
2)It is ten years ___ Miss Green returned to Canada.
A. that B. when C. since D. as
答案C. 考点是连词用法。 本题易误选为A. that. 其实本句不是强调句。若是，去掉It be… that还应是一个完整的句子。而本句去掉 It is…that，只剩下ten years Miss Green returned to Canada. 不成句。因此本句不是强调句。
It is /was +时间+ since… 其中is<---> has been was <---> had been.
三年级英语语法知识总结 (二)
现在进行时
表示正在发生的事情或进行的动作，常与now,listen,look等词连用，结构是主语+be动词(am, is, are)+动词ing.
如：It is raining now.
外面正在下雨
It is six o’clock now.
现在6点了
My parents are reading newspapers in the sitting room.
我父母正在客厅看报纸
Look! The children are having a running race now.
看!孩子们正在赛跑
问句将be动词移前，否定句在be动词后+not.
三年级英语语法知识总结 (三)
to 有两种用法：一为不定式+动词原形;
一为介词+名词/动名词， to 在下面的用法中是第二种，即to+ 名词/动名词：
admit to承认
confess to承认
be accustomed to 习惯于
be used to 习惯于
stick to 坚持
turn to开始，着手于
devote oneself to 献身于
be devoted to 致力于
look forward to 盼望
pay attention to 注意
三年级英语语法知识总结 (四)
一般现在时
表示经常反复发生的事情或动作，常与often, usually, sometimes, always, every day(week year…) on Sundays等词连用。
结构是主语+动词原形;当主语为第三人称单数即he,she, it, Tom, my mother, the boy等词时，动词后加s或es.
如：We have an English lesson every day.
我们每天都要上英语课
Do the boys run faster than the girls? Yes, they do.
男孩比女孩跑的快吗?是的
问句借助于do, does否定句借助于don’t, doesn’t，后面动词一定要还原。