怎么判断用is还是用do

判断使用is还是do,主要依据以下几点:

1. is用于连系两个名词或名词性物体,表示相等或相似的关系,如:This is a book. I am a student.

2. do用于表达动作,表示动作的执行或运用,后接动词原形,如:I do exercise every day. Do you play basketball?

3. is表示状态,性质或本质,do表示行为和动作。如:The sky is blue. What did you do yesterday?

4. is常与 appear, seem, look, sound等动词连用,表示"似乎"之意,如:She looks tired. The music sounds great.

5. is可用于被动语态的现在时和过去时,do不可用于被动语态。如:The work is done by him. The work was done yesterday.

6. is可与always, often, usually 等副词连用,表示习惯或特征,do不可与这些副词连用。如:He is always late.  *He does always come late.

7. do可以用于疑问句和否定句,is通常只用在陈述句。如:Do you like tea?  I do not like coffee.  *Is you like tea? *I is not like coffee.

8. do无人称变化,is有人称变化,如:I do, you do, he/she does.   I am, you are, he/she is. 

9. 常见固定搭配用is,如:to be honest, the reason is, the problem is 等。

综上,判断使用is还是do,需要考虑它们所表示的意义和用法区分,根据句子结构和内容选择最为合适的形式。实践和理解片语也很重要。掌握了这些规则和用法,选择is和do会简单很多。