— Hi, Susan, I didn’t see you at the party.— Oh, I ____ for an English test.
—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.