Help:oracle imp导入的character set不同的问题

我将一个dmp文件( ZHS16GBK character set )导入到我的oracle( US7ASCII character set ),显示如下所示错误:

Export file created by EXPORT:V09.02.00 via conventional path
import done in ZHS16GBK character set and AL16UTF16 NCHAR character set
import server uses US7ASCII character set (possible charset conversion)

请问应该怎样解决这个问题?

我将另一个dmp文件( ZHS16GBK character set )导入到我的oracle( US7ASCII character set ),成功了,但是表里数据的中文全部成了乱码,这又是为什么?应该如何解决?