21. There are records about the Diaoyu islands in      book published during the rule of Yong Le(1403-1424) in      Ming Dynasty, more than 400 years before Japan claimed the discovery of the Diaoyu islands in1884.

A. a; /                          B. the; /                        C. a; the               D. the; a

22. It is important to have your eyes examined regularly to check for any sign of eye diseased that may not have any      .

A. symptom                  B. similarity                 C. sample                     D. shadow