This machine, ______for many years, is still working perfectly.

A．after which I have looked

B．which I have looked after

C．that I have looked after

D．I have looked after

收益性物业价值的高低，主要取决的因素不包括( )。

A．未来净收益的大小
B．获得净收益期限的长短
C．获得净收益的可靠性
D．未来投资收益的潜力