ZhangHong appears _____ by heart 2000 words up to now.[ ]

A. to be learning    

B. to have learned    

C. to learn    

D. having learned

行痹的临床特征是：（）

A.关节酸痛，游走不定，恶风 

B.关节冷痛较剧，痛有定处，遇寒痛增，得热痛减 

C.关节疼痛重着，痛有定处，肌肤麻木，手足沉重 

D.关节灼热红肿，疼痛剧烈，得冷较舒。