the sun rising slowly in the east the scene is a perfect dream.A. SeeingB. To be seeingC

问题补充：

the sun rising slowly in the east, the scene is a perfect dream.

A. Seeing

B. To be seeing

C. When you see

D. Having seen

答案：

A. Seeing

B. To be seeing

(答案→)C. When you see

D. Having seen

解析：从句主语为the scene ，主句为you ，只能写成主从句。其他选项不合适

“当你看到太阳从东方慢慢升起时，这种景色确实太美了”