When he came back with plenty of money, his father _______ three days before.

Men and women can ________ people from all over the world by sending and receiving electronic mail.

— Has your son come back from abroad for the winter vacation?— Yes. But he stayed at home for only a week. Now he back to college.[ ]

Some students often find _______ difficult _______ remember the English words.

This pair of jeans looks nice ___________ me because I look nice ___________blue.