Bill,_____ you have fanished your homework,Let's go to fly kites now.

问题描述:

Bill,_____ you have fanished your homework,Let's go to fly kites now.
并请说明原因,

Bill,__SINCE___ you have fanished your homework,Let's go to fly kites now.
比尔,既然功课昨晚了,我们去放风筝.
since表示原因!