用天然骨料时，为减少弃料、减少总开挖量，常采取哪些措施？
参考答案：
①调整混凝土的配合比设计；②搭配人工骨料。
某无色透明溶液，能与Al作用放出H2，此溶液中可以大量共存的离子组是( )
A．OH-、Mg2+、Ba2+、Cl-
B．SO、Na+、HCO、K+
C．NO、OH-、Cl-、Ba2+
D．Cu2+、H+、SO、NO
It is important and necessary for us to wash our hands before eating, because we can
disease our bodies with the meals.
A, absorb, into B, take in, to C, suffer from, in D, take, out of
、Na+、HCO
、K+