`1.` `(+)` she is a good pupil.

`=>` `(-)` She isn't a good pupil.

        `(?)` Is she a good pupil?

`2.` `(+)` They are six years old.

`=>` `(-)` They aren't six years old.

        `(?)` Are they six years old?

`3.` `(+)` My father is a doctor.

`=>` `(-)` My father isn't a doctor.

        `(?)` Is my father a doctor?

`4.` `(+)` They are a teachers.

`=>` `(-)` They aren't a teachers.

        `(?)` Are they a teachers?

`=========`

`+` Công thức:

`-` Khi tobe là is thì sẽ đi vơi chủ ngữ số ít: It/ she/ he/ N(số ít)

`-` Khi tobe là are thì sẽ đi vơi chủ ngữ số nhiều: They/ we/ you/ I/ N(số nhiều)

They ( be ) six years old.

They are six years old.

My father ( be ) a doctor.

My father is a doctor.

Lan ( be ) good at English.

Lan is good at English.

They (be) teachers.

They are teachers.

form:

+S(they,we,people...)+are+0/adj

   S(he,she,it)+is+0/adj

    I(tôi)+am+0/adj

-S(they,we,people...)+aren't+0/adj

   S(he,she,it)+isn't+0/adj

    I(tôi)+am not+0/adj

? Are+S(they,we,people...)+0/adj

   Is+S(he,she,it)+0/adj

   Am+I+0/adj