21. Some researchers are finding that daydreaming may be important to ______ mental health. Daydreaming, they say, is ______ good means of relaxation.
A. the; 不填 B. 不填 ; the C. 不填; a D. 不填; 不填
22. Van Gogh succeeded in selling only one painting in his lifetime, and ______ was sold to his brother.
A. another B. that C. one D. which
