在线急等,C# BHO 变量类型转换,高手请进

[心如止水521]

[ComImport]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
[Guid("FC4801A3-2BA9-11CF-A229-00AA003D7352")]
public interface IObjectWithSite
{
[PreserveSig]
int SetSite([ MarshalAs(UnmanagedType.IUnknown)] object pUnkSite);
void GetSite(ref Guid riid, [MarshalAs(UnmanagedType.IUnknown)] out Object ppvSite);
}

using SHDocVw;
using Microsoft.Win32;

InternetExplorer explorer;

public virtual int SetSite( object site)
{
if (site != null)
{
explorer = site as InternetExplorer; //这句始终不能运行
}
}
return 0;
}

这个接口的setsite方法中参数pUnkSite为什么不能转换成其他类型变量

弄了好几天了,也没完成转换,快崩溃了

强制转换试过了,没有完成.