人力资本具有的基本特征是()。

A.人力资本是一种无形的资本

B.人力资本具有时效性

C.人力资本具有收益递增型

D.人力资本具有累积性

E.人力资本具有无限创造性

—Did your father come back early last night?

—Yes. It was not yet eight o’clock _______ he arrived home.

A．before

B．when

C．that

D．until