在强酸溶液中存在大量的Fe^2＋和Ba^2＋，那么在溶液中含有的离子是

A  NO₃^－    B  SO₄^2－    C  Cl^－    D  CO₃^2－

This is his only request that the room ______ after being used．

A．is cleaned

B．will be cleaned

C．would be cleaned

D．be cleaned