Most parents who are generous are good parents, but some self-centered parents are also good parents. Yet all good parents share one characteristic: they are good listeners.
If all of the statements in the passage are true, which one of the following must also be true

A．All parents who are good listeners are good parents.

B．Some parents who are good listeners are not good parents.

C．Most parents who are good listeners are generous.

D．Some parents who are good listeners are self-centered.

E．(E) Fewer self-centered parents than generous parents are good listeners.

在某无色酸性溶液中能大量共存的一组离子是

A．NH₄⁺、SO₄^2-、Al^3＋、NO₃^-

B．Na⁺、K⁺、HCO₃^-、NO₃^-

C．Na⁺、Ca²⁺、NO₃^- 、CO₃^2-

D．K⁺、Cu²⁺、NH₄⁺、NO₃^-