As is known to us all tiger is in danger of becoming extinct.A. the aB. the 不填C. a 不

问题补充：

As is known to us all, tiger is in danger of becoming extinct.

A. the, a

B. the, 不填

C. a, 不填

D. 不填, the

答案：

A. the, a

(答案→)B. the, 不填

C. a, 不填

D. 不填, the

解析：当概括事物的种类时，用定冠词，不用不定冠词；另外in danger of 是短语，不用冠词。