A-A+
The period during (when) people (learned to) s
问题详情
The period during (when) people (learned to) smelt iron is (called) (the) Iron Age.
A.when
B.learned to
C.called
D.the请帮忙给出正确答案和分析,谢谢!
参考答案
正确答案:A
解析:本题考查“介词+which”引导定语从句。when不用在介词后。改“when”为“which”。