The best way to learn proper English is to read news report, and watch news on TV. Watching TV shows is a great way to learn casual English, slang words, understand culture reference and humor. If you have already watched these shows then you may recall the words used in the following dialogs.

Week in and WEEK out,
from the time I was 5...
The Big Bang Theory Season 3, Episode 6

She wanted to sell them, I said okay,
and in one WEEK, I made a $156.
The Big Bang Theory Season 2, Episode 18

See you next WEEK.
The Big Bang Theory Season 1, Episode 5

I can't help it if you got
your days of the WEEK wrong.
Breaking Bad Season 2, Episode 1

that's for the WEEK.
Breaking Bad Season 4, Episode 8