_____ he was tired, _____ he didn’t stop to have a rest.
—What colour of the following represents “purity”? —______.
—Do you have any difficulty______ the work in two days?
—White doesn’t look good _______ you,but you look cool _____ black.
—The green bag reminded the old man _____ the days when he was young.
—We find ______ impossible for us to learn a foreign language well in a short time.