---Mr. Black, I find ______ difficult to play the piano well.---Oh, I think you just need to practice more
—What do you think of Project Hope? —Great! It has made important contributions _____the education.
The traffic in the city _____ be terrible, but now it has improved a lot. I think you will ____ it soon.
—How long has Kangkang _____from home? —For five days.
—I have never visited the Great Wall. —_____.
There are ninety teachers in our school. _____ of them are men.