--- I didn’t see you at the party yesterday. Why? --- Because I ________ for an important person from America at that time.
—I have never visited the Great Wall before。. —___ _________
The study of English ___________ a very important industry in China.
Her husband _____ for 20 years, but she still lives lonely.
Trees can stop the sand _____ towards the rich farmland in the south.
This is the most beautiful butterfly I have _____ seen in my life..