Oxygen is an important element we can’t live. A. from which B．from that C．without that D．without which 【查看更多】

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用恰当的关系词或者介词+关系词填空。

1. This is the biggest lab ______ we have ever built in our university.
2. Air, ______ we breathe every day, is around us all the time.
3. He is a man of great knowledge, ______ ______ much can be learned.
4. The man, in ______ bag you found your lost money, has been sent to the police.
5. The village has developed a lot ______ we learned farming two years ago.
6. Who ______ has common sense will do such a thing?
7. The reason ______ he didn't come was that he was injured.
8. Oxygen is a kind of gas, ______ ______ we couldn't live.
9. I was surprised at the way ______ he treated the old man.
10. We are living in an age ______ many things are done on computer.

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Chemical Change and Physical Change

　　There are two kinds of changes－chemical change and physical change．

　　In a chemical change, there is always a new substance formed．Breaking up water into hydrogen and oxygen is a chemical change．In each of the chemical change at least one new substance is formed．A change is not a chemical change if it doesn’t form a new substance．

　　Physical changes are very common, too．There are many examples．You can make a physical change by tearing a piece of paper into two, or by cutting a piece of iron with lathe．Here paper is still paper, and the iron is still iron．

　　Another way of making physical change is dissolving something in water．When you dissolve salt in water, the salt disappears．You may think that a new substance has been formed．But really there is no new substance．The salt is still salt．You can still taste it．So the dissolving of anything is a physical change．

　　When water freezes, the change is also a physical one．The water changes from liquid to solid．But it is still the same substance．That is why the freezing of anything is a physical change．

(1)

It is not ________ if a new substance is not formed in the change．
[　　]
A．	a physical change
B．	a chemical change
C．	a change of state
D．	a change