Why does abstract class need to implement interface members?

See the following code: Public interface ICreateTime
{
DateTime CreateTime
{
Get;
Set;
}
}

Public abstract class EntityBase: ICreateTime
{
Public EntityBase ()
{
CreateTime = DateTime. Now;
}
}

Is it intuitive?
But no, compilation cannot pass: 'entitybase' does not implement interface member' ICreateTime. createtime '. I know it is not implemented. Why should I mark it as abstract? I don't want to leave it to the subclass implementation?

After being depressed for a long time, I finally figured out why C #Implementation InterfaceAndOverride base class MethodThe difference is that C # compiler is too lazy. If Java does, it will automatically tell which methods are virtual and which ones are not convenient ..