一道高考英语单选
I walked in our garden, ____ Tom and Jim were tying a big sign onto one of the trees.
B. when C. where
选出正确的选项
并说明另一个为什么不对
参考答案:如果是WHEN，就不是定语从句，是状语从句，状语从句不用逗号的，做了那么多的题，还没哪个状语从句是用逗号的！
WHEN是解释为当……时
I walked in our garden whenTom and Jim were tying a big sign onto one of the trees
所以选C