—I have never been to the Great wall. —If you have an opportunity _______ there, you must take it.
He met many problems------ he was going over his lessons.
One of the wonders of the _____ world is the pyramids in Egypt.
We all agree that a pair of shoes _____________a nice present.
—Hello, this is Amy. Is Tom there? —___________________
—How was your day, Linda? —________________