You see, “Food Safety” receives thousands of Internet hits a day.—Obviously, it has become one of the _________ topics recently.

I stay at home _______ on weekends, but I don’t feel ______..

The classroom is clean it was yesterday.—Sorry, I forgot to clean it.

She had an advantage over others because she had a good ________ of both Chinese and English.

About ______ of the books in our school library are written in Chinese.