—Will you give me a hand? I have some trouble_______ the scientific problem.—Don't worry. I'll try my best to help you _______.
Which scarf is ______, the green one or the blue one?
I want to buy some postcards in the shop, ______ I don’t have enough money.
—______ is your best friend? — Linda, I guess.
—Lily, how do you usually come to school every day? —Usually ______ bike.
Mr. Black is very kind to others. We all like ______ very much.