—Anything special in today’s papers?

—Yes. “Confidence is more important than gold” by Premier Wen ________as a headline in many of today’s newspapers.

A．is used

B．are used

C．has used

D．have used

限用一种试剂, 经过一次性实验就能鉴别下列四种溶液：Na₂CO₃、(NH₄)₂SO₄、NH₄Cl、KNO₃, 应选用：

A．AgNO₃溶液

B．NaOH溶液

C．盐酸　

D．Ba(OH)₂溶液