They have invited me to their party, ________ very kind of them．

They have invited me to their party, ________ very kind of them．

A.it is

B.that is

C.as is

D.which is

答案及解析： D

本句是非限制性定语从句句型，选D项，选项A也是非限制性定语从句句型，但as在这里意思不当。