Learn it by heart

I ......... don't know how to learn new words by heart.
some time
sometimes
something

I often read short articles ......... pets in my favourite magazine.
for
at
about

I think learning ......... be interesting because otherwise you wouldn't ever be able to succeed.
can
should
must to

You will probably agree ......... me.
with
for
in

If you have a question please feel ......... to ask.
good
well
free

Thank you very much indeed, that's very kind ......... you.
from
for
of

We are really glad to have you as our ......... and we will take good care of you.
containers
customers
costumiers

For the whole of next week we are planning to sell our new dictionaries at a special ..........
price
prize
prise

As of now we still don't know if we will be ......... to fulfil our contract.
reliable
able
capable

Don't worry, we are quite flexible and can make changes at ......... time whatsoever.
some
any
one