动态RAM与静态RAM的主要不同点在于什么？
参考答案：在于动态RAM需要刷新
I believe that the 21st century is one ______ China will become one of the most powerful economic countries.
A．which
B．that
C．when
D．where
异步电动机三相空载电流严重不平衡有哪些原因？
