about to (do something)

- to be on the point of doing something

I was about to leave when the phone rang.

according to (someone or something)

- as said or told by someone, in agreement with something, in the order of something, in proportion to something

According to our teacher, there will be no class next week.
We did everything according to the terms of our agreement.

account for (something)

- to provide an explanation or answer for something

The bad weather accounts for the fact that few people came to the meeting.

after all

- considering the fact that something happened, something that is usually assumed

"You don't need to phone him. After all, he never phones you."

all of a sudden

- suddenly, without advance warning

All of a sudden it became cloudy and began to rain.

as a matter of fact

- actually

"As a matter of fact, we have been to the history museum many times."

as far as

- to the extent or degree of something

As far as I know the movie will start in a few minutes.

as for

- with regard to, concerning

"As for me, I think that I will return home now."