—Hi, Jack, there is ________ useful book on the desk. Whose book is it?— It belongs to my brother.A. a B. an C. the
—Where is Mr. Wu? I haven’t seen him for several days. —He ________ America and he ________ from his home since last week.
—How long have you learned English? —So far, we ________ English for more than six years.
Timmy likes Chinese very much. He can’t stop ________ it every day.
We are _____to see so many interesting books in the library. Now we have _____ to read.
—What do you usually use your computer ________? —I usually use it to search for information.