Sometimes a few words of _____ from his teacher to the one who has just failed in the exam may encourage

him to stand up. [ ]

A. compromise

B. confidence

C. comfort

D. consultant

下列离子方程式的书写正确的是                                        （   ）

A．实验室用大理石和稀盐酸制取CO₂： 2H⁺ + CO₃^2- ＝ CO₂↑+ H₂O

B．铁和稀盐酸反应： 2Fe + 6H⁺ ＝3H ₂↑+ 2Fe ³⁺

C．稀硫酸与锌反应：H₂SO₄+Zn=Zn²⁺ +SO₄^2-+H₂↑

D．NaHCO₃溶液与NaOH溶液反应： OH^- + HCO₃^-＝ CO₃^2-+ H₂O