It seems as if the sun_____round the earth since it rises in the east and sets in the west.
D
“asif”“似乎，好象”，太阳并不是绕着地球转，所以后面应该与事实相反的假设，要用虚拟语气。需要特别指明的是：“如果是一般的客观规律的陈述，则用一般现在时”。
He‘s working hard_____.
He‘sworkinghard_____.
It was not until she had finished all her work_____.