英语当中有几种句型呢？就两种，陈述句和疑问句。
陈述句又分为：肯定句和否定句。
疑问句又分为：一般疑问句，特殊疑问句和选择疑问句。
这几个句型之间有没有联系，如果是一个句子的句型变化，它们是打断腿连着筋，关系密切着呢！来，上图，我们用中文来看这几个句型有什么关系。
今天，我们就来讲讲，肯定句变成否定句的方法。
句子可以分成：be型句，can型句和助型句。
【be 型句】顾名思义，就是句子当中含有be(am/is/are/was/were)的句子。
口诀：
例子：肯定句：She is going to China next month.
否定句：She isn’t going to China next month.
肯定句：There were some ducks and chickens on the farm too.
否定句：There weren’t any ducks or chickens on the farm either.
肯定句：I am a teacher.
否定句：I am not a teacher.
【can型句】是句子中含有can的句子吗？
这里指的是含有can这样的情态动词的句，情态动词有哪些？常见的如下：
例子：
肯定句：I can play the pianno well.
否定句：I cannot play the pianno well.
肯定句:His family will fly to Beijing.
否定句：His family won’t fly to Beijing.
肯定句：The little boy should go to bed early.
否定句：The little boy shouldn’t go to bed early.
【助型句】你猜的没有错，就是句子当中需要助动词帮助完成转化的句子。
句中无be无情时；口诀（七年级以下），
这里需要解释，动原就是动词原形
动三就是动词的三单形式；比如finish–finishes
动过就是动词的过去式; 比如finish–finished
例子：
肯定句：The students often sing songs after school.
否定句：The students don’t often sing songs after school.
肯定句：The boys runs fast.
否定句：The boys doesn’t run fast.
肯定句：The king showed his new clothes to us.
否定句：The king didn’t show his new clothes to us.
今天就更新到这，仍然给大家留一些练习。
