How to form Yes/No questions

The rules

1.If the main verb of the sentence is "to be", simply invert the subject and the verb to be:
Examples:

• They are American. — Are they American?
• They are nice. — Are they nice?

2.If the sentence includes a main verb and another or other helping (auxiliary) verb(s), invert the subject and the (first) helping (auxiliary) verb.
Examples:

• They are visiting Paris. — Are they visiting Paris?
• She has done the housework. — Has she done the housework
• Nancy has been working all night long. — Has Nancy been working all night long?
• He will be reading the book. — Will he be reading the book?

3.If the sentence includes a verb which is not the verb "to be" and doesn't include a helping (auxiliary) verb, the transformation is more complex.

a.If the verb is in the present tense, add either do or does and put the main verb in its base form:

• do if the subject is the first person singular, second person singular, first person plural, second person plural and third person plural (I, you, we, they)
  Examples:
  I like apples. — Do you like apples?
  They go to a high school. — Do the go to a high school?
• does if the subject is the third person singular (he, she, it).
  Examples:
  Nancy reads a lot. — Does Nancy read a lot?
  He hates basketball. — Does he hate basketball?

b.If the verb is in the past tense, add did and put the main verb in its base form:
Examples:

• He discovered the truth. — Did he discover the truth?
• She write a nice essay. — Did she write a nice essay?
• They did the homework. — Did they do the homework?

There is an exercise here.