---Have you read this book ?---Yes . I _____ it two weeks ago .
The railway Qinghai to Tibet is the longest plateau (高原) railway in the world.
I find ____ useful _____ English well.
.We may meet all kinds of difficulties in the future, but we should be confident enough to --- any challenge.
— It’s dangerous to walk across the street carelessly. — You’re right. We can’t be careful while crossing the street.
----It seems that it will rain. Take my umbrella. ---- _______. I have a raincoat in my bag.