The math problem is _______ difficult and _______ of them can work it out.
—How do you improve your listening skill, Mary?—I often do it _________ tapes and English radios.
After a 3-week winter vacation, students usually some weight when they return to school.
Dear students, please read the passage carefully. _______you are ____mistakesyou’ll make.
—What did Tina say?—Sorry, I didn’t________what she said.
—The Internet has made communication much . —I agree. For example, I can communicate with my friends on WeChat any time.