MRI装置所不包含的内容有( )
A．磁体系统
B．梯度磁场系统
C．高压发生系统
D．射频系统
E．计算机系统
参考答案：C
She did the exercise again. She forgot _____ it. [ ]
A. to do
B. doing
C. do
D. did
试述宋初的复古思潮。
