21. As only one chapter of the novel was published __________ in the newspaper, many readers preferred to buy a copy of the novel.

A. at one time              B. at a time            C. at times                  D. in time

22. __________ as one of the most talented artist in European history, Van Gogh couldn't have sold a single work without his brother’s assistance.

A. Thinking               B. Said                   C. Viewed¡¡¡¡¡¡¡¡¡¡¡¡      D. Considering

23. South Korea can __________ be called a friend of China, though it shares China’s negative feelings about Japan .

A. hardly                 B. just                  C. almost                  D. possibly