_HTHH:

We've been to Singapore a lot over the last few years.

She's done this type of project many times before.

The army has attacked that city five times.

I have been a teacher for more than ten years.

How long have you been at this school.

They haven't known yet.

She hasn't arrived yet.

They've already met.

I think I have seen thật move before.

Has he ever talked to you about the problem.

_HTD:

The flight starts at 6 a.m every day.

My mother often teaches me English on Saturday evenings.

The moon circles around the earth.

_HTTD:

I'm playing video games.

Is thật computer working.