_______ the sun sinks lower, shadow spread ________ the courtyard.

_______ the sun sinks lower, shadow spread ________ the courtyard.

A.When; through

B.When; across

C.As; through

D.As; across

答案及解析： B

解析：

前句为时间状语，后句为扩散到-----,此处有漫过、穿过之意。