21. This book _____ forty maps, _____ three of Great Britain.
A. contains; includes B. is containing; including
C. includes; contains D. contains; including
【解析】选D。本题考查contain和include 的辨析。forty maps是这本书全部的内容，应用contain; three of Great Britain是其中部分内容，应用include。contain没有进行时态，故B错误；include应用现在分词形式作状语，故A错误，正确的只有D。
