With time going by, we have come to realize that creativity is _______it takes to keep a nation highly competitive.
—Shall I give you a hand with this as you are so busy now?—Thank you. ______.
—Might I have some more bread?—Yes, _______.
At present a special village _______ for the athletes from different countries to live in.
—Timmy, it is raining heavily out. Shall we stop here?—_______, we must finish this work today.
When his father came into his room, Tom pretended _______ a book.