某溶液中可能含有H+、Na+、NH4+、Mg2+、Fe3+、Al3+、SO42—、CO32—等离子。当向该溶液中加入一定物质的量浓度的NaOH溶液时,发现生成沉淀的物质的量随NaOH溶液的体积变化的图象如下所示,下列说法正确的是( )
They use computers to keep the traffic _______ smoothly.
If you leave the club, you will not be_____back in .
What I need is_____ book that contains ______ABC of oil painting.
Jenny nearly missed the flight______ doing too much shopping.
The CDs are on sale! Buy one and you get ______ completely free.