He was going back and forth between the office and home all day.

I'm just going to the supermarket, okay?

I will go to the library and come back.

He comes home from school every day.

His attitude really makes me mad.

He said he would come right away.

That idea is just right, exactly what we needed.

He is scheduled to come back in a week.

It is reported that North Korea has conducted another underground nuclear test.

Groundwater pollution has become a serious environmental problem.