单选题Einstein’s theory of relativity seemed hard to believe at the time when he was first introduced.A when he first introducedB that he first introduced itC he first introducedD which he first introduced it
题目
单选题
Einstein’s theory of relativity seemed hard to believe at the time when he was first introduced.
A
when he first introduced
B
that he first introduced it
C
he first introduced
D
which he first introduced it