There is long way to go for scientists to study space.A. aB. anC. theD. /

问题补充：

There is long way to go for scientists to study space.

A. a

B. an

C. the

D. /

答案：

A. a

B. an

C. the

(答案→)D. /

解析：space 为专有名词，在专有名词前一般不用冠词，属于零冠词情况。