John said he`d been working in the offic for an hour ,_____was true1.he2.this3.which4.who要原因

John said he`d been working in the offic for an hour ,_____was true1.he2.this3.which4.who要原因
John said he`d been working in the offic for an hour ,_____was true
1.he
2.this
3.which
4.who
要原因

John said he`d been working in the offic for an hour ,_____was true1.he2.this3.which4.who要原因
3.which 非限制性定从,指逗号前整个句子

3 是非限制性定语从句 只能用which

后面只能跟从句，所以1和2都可以排除。非限制性定语从句此处只能用which,用来指代前面的情况he`d been working in the office for an hour。

只要有逗号，后面就是which 这是一般答题技巧