龚自珍的（）的文章有（）等。
参考答案：成组；《明良论》、《乙丙之际著议》、《壬癸之际胎观》、《古史钩沉论》
He __________ his position as the manager of the department because he was offered a better job.[ ]
A．regained
B．repeated
C．represented
D．resigned
设函数y=y(x)由参数方程
所确定，则
=______.
所确定，则
=______.