The boy sitting by the window is the only one student who ( ) from the country .

问题描述:

The boy sitting by the window is the only one student who ( ) from the country .
A.is .were C.was D.are

答案是A.is
who is from the country 做前面the only one student的定语
定语从句的时态一般要与主句的时态保持一致,所以选is而不是was