The sun rises in the east and sets in the west so it seems as if the sunround the earth.A.

问题补充：

The sun rises in the east and sets in the west，so it seems as if the sunround the earth.

A. were circling

B. circles

C. is circling

D. be circling

答案：

(答案→)A. were circling

B. circles

C. is circling

D. be circling

解析：as if引导的从句要求用虚拟语气，动词要用过去时（be动词用were）或would(could等)+动词原形，本句话中指的是当时的情况，所以要用过去式，故A是正确答案。