为提纯下列物质(括号中为杂质),所选除杂试剂和分离方法都正确的是
It’s high time you had your hair cut ; it’s getting _______ .
My friend showed me round the town, ______ was very kind of him.
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.