The moment she came back from work,she___to clean the kitchen thoroughly
Professor Smith will come here to give a speech. All the preparations must be _____ before 5 o’clock.
---Is everything settled? ---Not yet. _____ I approached the problem, I couldn’t find a solution.
The retired professor, _____ in his new book in the past three years, hasn’t realized the decline in his health.
With the final exams coming, Mark, the top student in our class, is not worried about Chinese, and _________ English.
It puzzles the scientists _____ some mammals produce their young _____ others lay eggs.