题目

So long as we study with a strong will，we can answer the question__________hard it is. A.no matter what                               B.how C.whatever                                        D.however 答案：D 解析: however引导让步状语从句，相当于no matter how,意为“无论如何；不论到什么程度”，后面接形容词或副词。又如：However tired you may be，you must do it today.不管怎样累，你也得今天做。下列各组离子在相应的条件下可以大量共存的是 [     ]A．在碱性溶液中：CO32-、K+、Cl-、Na+ B．与铝粉反应放出氢气的无色溶液中：NO3-、Mg2+、Na+、HCO3- C．在c(H+)/c(OH-)=1×10-12的溶液中：NH4+、Ca2+、Cl-、K+D．在酸性溶液中：Fe2+、Na+、NO3-、Cl-