I'm sorry that you don't like the present, ________because I bought it________for your birthday.
As ________ clear from his manners, he seems to be much of a scholar.
While he was investigating ways to improve the telescope, Newton made ____ discovery which completely changed ________ man’s understanding of color.
He never does anything wrong. He should be the ________ to blame.
Reading provides the mind only with materials of knowledge; it is thinking that makes ________ we read ours.
We have done things we ought not to have done and ________ undone things we ought to have done.