下列反应的离子方程式书写正确的是
A．硫酸铝溶液中加入过量氨水 Al3+＋3OH－ ＝ Al(OH)3¯
B．电解饱和食盐水 2Cl-＋2H2O
H2↑＋Cl2↑＋2OH-
C．钠与水的反应 Na＋2H2O ＝ Na+＋2OH- ＋H2↑
D．单质铜与稀硝酸反应 Cu + 2H++ 2NO
= Cu2+ + 2NO↑+H2O
答案：B
A:氨水为弱碱，不能拆为离子，排除
B：正确
C：电子的得失不守恒：2Na＋2H2O ＝2 Na+＋2OH- ＋H2↑，排除
D：电子得失不守恒：3Cu + 8H+ + 2NO
= 3Cu2+ + 2NO↑+4H2O，排除
答案为B
A mother planted many kinds of vegetables in her garden. One day, she said to her , “Betty, come here. Look at all these little yellow marks（斑点）on the of the cabbages ( a kind of vegetable ). They are eggs of a kind of insect. They are very beautiful but very bad for cabbages. This afternoon you must all the eggs on the leaves and kill them. In this way, you will help us have , greener and bigger cabbages.” Betty didn’t think she could do it and in the end she forgot all about it. The mother fell ill for a few days and work in her garden. When she was well, she took Betty with her to the garden to see the cabbages. To surprise, the insects have eaten every leaf. When Betty saw this, she began to . Then her mother said to her, “We should never put off（推迟）what we have to do today till . And you must learn to deal(处理) with the bad things they are small, or it will turn into a big problem.”
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