判断历史β值是否可以指导未来的关键因素有（）

A.经营杠杆

B.成本的周期性

C.收益的周期性

D.财务杠杆

So quickly ________ is a possibility today may be a reality tomorrow.

A．are science and technology advancing that

B．science and technology advancing are that

C．science and technology are advancing what that

D．are science and technology advancing that what