Adverbs of time indicate when something occurred, and also how often, and for how long.
When: last week, tomorrow, now, last week
For how long: all week, since last month, not long
How often: seldom, weekly, never
These types of adverbs are generally put at the end of the sentence:
John went to his girlfriends house yesterday.
She is going to wash her car next week.
Sometimes when adverbs can be put in other
positions within the sentence to give a different meaning or emphasis.
For example:
Later he drove to the airport. (the time is more important)
He later drove to the airport. (this is more formal)
He drove to the airport later. (this is neutral, there isn’t a particular
emphasis)
For how long adverbs generally are put at the end of the sentence:
John stayed at his girlfriends house all day.
She lived in America for 2 years.
Important point: ‘for’ is always followed by an expression of duration:
for 1 month,
for 10 minutes,
for a month,
for a lifetime.
‘since’ is always followed by a statement of a point in time:
since last week,
since the year 2000,
since our last meal.
“How often” adverbs expressing the frequency of something usually are put after auxiliary verbs (like be, have, may,must) but before the main verb:
I frequently eat out at restaurants. (before the main verb)
I never drink Wine. (before the main verb)
You should always wear your motorcycle helmet. (after the auxiliary must)
He is never sick. (after the auxiliary is)