The U.S. first lady Michelle Obama, arrived in China on March 20, 2014 for _______ six-day visit, focusing on _______ importance of cultural exchanges.
Our teacher said sound___much more slowly than light.
Will you please show me the way to the only tall building ___stands near the post office?
—Look! The boy in the white shirt ___be Tom. --It ____be him. I saw him enter the library just now.
Students should do everything they can __their study.
If you are a little careful, I think you can _____the problem.