____ is it from Shanghai to Shijiazhuang?— Two thousand kilometers. [ ]

The number of books in the bookshop is about 10,000 and a number of them about science.

How many birds can you see in the trees?—I can see birds in them.

Betty always ________ me some questions but I can’t answer all of them.

Do you find _______ difficult to be independent(独立的)?.