________ made us surprised that the students even didn't know ________ the difference between the two words lies.
A.What; whereB.It; whereC.That; whereD.It; what在线课程B
第一空用it作形式主语，真正主语是随后的that从句，此空不能用what；第二空用where引导宾语从句，引导词在从句中作状语。