(2013·高考重庆卷)—What are  you doing this Saturday?—I’m not sure，but I________go to  the Rolling Stones concert.

-----Who ______ it be that hasn’t handed it in yesterday? ------It _______ be Bob. He handed it in yesterday.

－ Look! Mrs Green is wearing a black dress today.－ I think she _______ wear red. She looks young in red.

Sometimes most of us probably are angry______our friends, parents or teachers. 

It was playing video games that took the boy too much time that he          have spent learning．