It is easier to float in the ocean than it is to float in a swimming pool. Do you know why?
Ocean water is full of salt— and salt water can hold up more weigh than fresh water. See for yourself!
You Will Need:
● 3 cups of warm water
● Measuring cup (量杯)
● Wide-mouthed jar
● Salt
● Spoon
● Raw (生的)potato
You Will Do:
1. Pour 1.5 cups of warm water into the jar.
2. Add 1/3 cup of salt.
3. Stir(搅拌) until the salt is completely dissolved.
4. Add another 1.5 cups of water. Pour it slowly over the back of the spoon into the jar so that the two liquid will not mix together.
5. Gently place the potato into the jar. Do not drop it.
What Will Happen:
The potato will sink— but only halfway!
Why?
Salt water is heavier than fresh water, so it will stay on the bottom. The fresh water will remain on top.
The potato is heavier than the fresh water, but it is lighter than the salt water. That is why the potato will sink halfway down

1.In the experiment, what should you do right after you pour the water over the spoon?

1. A.
   Add the salt to the water
2. B.
   Stir the salt into the water
3. C.
   Place the potato in the jar
4. D.
   Pour warm water into thejar

2.In Step 4 of the experiment, why do you pour the water over the spoon “slowly”?

1. A.
   It is easier to see what you are doing
2. B.
   It pushes the fresh water to the bottom
3. C.
   It will keep the water from coming out
4. D.
   It will keep the liquids from mixing together

3.In which step of the experiment do you add the salt?

1. A.
   Step 1
2. B.
   Step 2
3. C.
   Step 3
4. D.
   Step 4

4.What does the underlined word “gently” mean?

1. A.
   Carefully
2. B.
   Quickly
3. C.
   Secretly
4. D.
   Silently

--- I wonder whom you are waiting for.
--- The policeman ______ the traffic accident.

1. A.
   dealt with
2. B.
   to deal with
3. C.
   will deal with
4. D.
   did with

--- ______ at the New Century Cinema tonight?
--- Avatar, a Hollywood science fiction by James Cameron.

1. A.
   What’s on
2. B.
   What’s up
3. C.
   What’s the matter
4. D.
   What will happen

---Hello, Sally. How’s everything going?
---______.

1. A.
   The same to you
2. B.
   I can’t agree more
3. C.
   Not too bad
4. D.
   That’s right

---Have you thought about what to do next?
---______ I know my business.

1. A.
   What for?
2. B.
   Why not?
3. C.
   Don’t worry
4. D.
   No wonder.

The patient was in bad need of operation but there was no guarantee(保证) that she would survive the anaesthetic (麻醉剂), which made the doctors on the horn of a __________

1. A.
   process
2. B.
   arrangement
3. C.
   ceremony
4. D.
   dilemma

---Is there any vaccine(疫苗) against H1N1 flu that can be used on humans?
---No, but scientists are working to develop ______.

1. A.
   that
2. B.
   it
3. C.
   one
4. D.
   so

She was moving out of her old apartment ______ she suddenly realized that the key to the new apartment wasn’t on her.

1. A.
   until
2. B.
   once
3. C.
   when
4. D.
   as if

Lu Xun ______ a lot of novels.

1. A.
   wrote
2. B.
   had written
3. C.
   was writing
4. D.
   has written

---Do you have anything in mind______ you’d like to have for dinner?
---Well, ______is okay for me.

1. A.
   that;anything
2. B.
   which;everything
3. C.
   what;nothing
4. D.
   where;something