I’ve heard that the wood tower was built more than 1,000 years ago, so I think it is worthy ________.
The use of Chinese by teachers in ______ English classroom must be restricted because it will decrease _______ time when students are exposed to the English language.
You can take ____ you like here.
It is said that his carelessness ____ the terrible accident.
Tom as well as his friends ____ to visit our school soon after they arrive in Changsha.
By the time you ____ in, I ____ two letters.