A:has been going on; haven’t reached.
B:has been going on; haven’t been reached.
C:was going on; haven’t reached
D:was going on; haven’t been reached
九年级2班的同学在教师指导下用如图所示的实验装置进行“观察冰熔化”的实验.
关于惯性的大小,下列说法正确的是 ( )
"文化大革命"中最大的冤案得到平反是在( )