Please correct the following sentences.

1) He can't come to the office as he is sick.

2) He has left this place with all his family members.

3) The dowry system has been prevalent from times immemorial.

4) He is critically ill; there is a little hope of his recovery.

5) There are no less than fifty students in the class.

6) Your method is preferable than his.



All good, except that in (6), the preposition is 'to':

- Your method is preferable to his.

If you were using a comparative adjective (usually ending in -er) then 'than' would be right:

- Your method is better than his.