下列离子组在一定条件下能大量共存,当加入相应试剂后会发生化学变化,且所给离子方程式正确的是
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.