--You don't look so well, Mary. What's the matter with you?--Why?___________.
______, most of the spelling mistakes can be avoided.
—Which of the two books will you take? —I’ll take ______and I think______ of them is really helpful to me.
The number of Chinese speakers in the world ________with the development of China is much larger than ever before..
Little Jill can’t understand the way ______her brother visited the neighboring cities.
Can you tell me ___________________? You look upset.