known to us increasing number of students are buried in their studies.A. What is;aB. It i

问题补充：

known to us, increasing number of students are buried in their studies.

A. What is;a

B. It is;the

C. As it is;the

D. As is;an

答案：

A. What is;a

B. It is;the

C. As it is;the

(答案→)D. As is;an

解析：本题考查定语从句和冠词。“，”前后都是句子，可判断第一个空应用连词，排除B项； a number of +复数名词+复数谓语动词；而the number of +复数名词+单数谓语动词；再结合are及increasing可知第二个空应填an。句意：众所周知，专心学习的孩子越来越多。