Some verbs need a specific preposition before an object or another verb.
The preposition is only grammatical, so it doesn't change the meaning of
the verb.
Here are some of the most common verb + preposition combinations...
speak + to
For example:
I usually speak to my parents at the
weekend. Susan is speaking to her boss.
Yesterday the Prime Minister spoke to the
Queen.
look + at
For example:
They look at the birds in the garden. Will
you look at my project, please?
I love looking at old photos.
agree + with
For example:
I agree with you.
Do you agree with the plans to build a new
motorway?
He didn't agree with his wife's idea.
depend + on
For example:
The price depends on the demand.
Young children depend on their parents.
The plan depended on the weather.
worry + about
For example:
Don't worry about the future.
Are you worried about the exam? She was
worried about her health.