Confused Prepositions

Using after for in

Rule: in is used for denoting a period of time in future.

Incorrect Usage: I may be able to meet you after a week.

Correct Usage: I may be able to meet you in a week.

              I may be able to meet you in a week’s time.

Confused Prepositions

Using since for for

Rule: The preposition for should be placed before phrases denoting time period.

Incorrect Usage: He was in prison since two years.

Correct Usage: He was in prison for two years.