In the forest we observed some trees ____the leaves were black with disease.
| A．where | B．of which | C．in which | D．whose |
Before you pay a visit to a place of interest, look in your local library________a book about it.
| A．on | B．at | C．for | D．to |
Everything comes with ________ price；there is no such ________ thing as a free lunch in the world.
| A．a；a | B．the；/ | C．the；a | D．a；/ |
Many people agree that ________ knowledge of English is a must in ________ international trade today.
| A．the；an | B．a；/ | C．the；the | D．/；the |
In the market，vegetables are sold by ________ kilogram，I mean，by ________ weight.
| A．the；/ | B．/；/ | C．the；the | D．/；the |
—John has put forward ________ most challenging question for us to answer.
—Yes，it really is.I have never heard ________ harder one.
| A．the；/ | B．/；the | C．the；the | D．a；a |