. While he was investigating ways to improve the telescope, Newton made discovery which completely changed man’s understanding of color.
When the man came in, gun in hand, we all stood there, ________.
If nature does not provide man with the necessary material, it is the laboratory ____ he will turn to for it.
By the time you have completed the essential training, you _____ exposed to virtually every new feature of the course.
_______ more to be pitied than blamed.
Earth is believed ______ by an object the size of Mars at some point in the distant past before its surface cooled.