You can not imagine the difficulty they had ____ the problem. It isn’t ____ easy.

I met a friend of mine_________ in the street yesterday.We didn’t meet on purpose. [ ]

Could I look at your pictures? — Yes, of course you _____.

My friend _______ to visit me in a week. –That’s good news for you.

Look, There’s __________ sheep on the hill and there are _______ children, too.