6．What great progress you have achieved in such short time!A. a ; aB. / ; aC. / ; /D. a;

问题补充：

6．What great progress you have achieved in such short time!

A. a ; a

B. / ; a

C. / ; /

D. a; the

答案：

A. a ; a

(答案→)B. / ; a

C. / ; /

D. a; the

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