the usage of "both" and "all"

[michelle]

Hi there,
In the following sentences, which ones are correct?

(1) Both they are students.
(2) They both are students.
(3) They are both students.
(4) Both the girls are students.
(5) The girls both are students.
(6) The girls are both students.

Any of your feedbacks will be highly appreciated. Thanks.

Michelle

[schetin]

Hi Michelle,

(2) and (4) are correct.

My ha'p'orth,

Slava