I phoned you at six yesterday afternoon, but nobody answered.— Oh, I __________a walk with my parents near the river.

A computer is very popular and helpful .— I think so. It _______ in many different fields.

You must remember _______ the window before you leave.

I’d like to introduce my best friend to you , Peter .—- Thank you , Lucy . But we __________already .

His book is wonderful. I ______ it for three times.