—What’s the matter with you? You look so worried.-- I don’t know ___________ the problem.
I’m sorry to have kept you________for almost two hours.
My mother often hears me________in my room.
I didn’t sleep well last night,so I felt________this morning.
I failed the exam.What________news!My parents said that they were________at my grades.
—Do you like red or pink? —________.I like black.