不是星系在空间中做退行运动，而是空间自身在（）。
参考答案：膨胀
—Hi,Robert,Bob has come back from abroad.Let’s have a get-together this weekend,shall we?
—___________.
A．It’s my pleasure
B．Great idea
C．It’s quite all right
D．It’s very kind of you
基金证券，股票和债券的区别
