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Grammar Focus

A Check the correct sentences.

1 a. However, over 97 percent of the water on the Earth is salt water in the
oceans.

b. However, over 97 percent of the water on the Earth are salt water in
the oceans.

2 a. Do you worry what we will run out of fresh water?

b. Do you worry whether we will run out of fresh water?

3 a. Water vapor in the air cools and condenses into tiny droplets.

b. Water vapor in the air cool and condense into tiny droplets.

4 a. Bunches of tiny droplets collect into clouds.
b. Bunches of tiny droplet collects into clouds.

5 a. Some of the water evaporate back into the air.

b. Some of the water evaporates back into the air.

B Choose the correct words to complete the sentences.

1 Animals need water ( survive / to survive ).

2 Only 3 percent of world’s water ( is / are ) fresh water from rivers and
lakes.

3 When the sun ( heats / will heat ) up the water, it evaporates into the sky.

4 If you put water in the sun, why does it ( evaporate / evaporates )?

5 In this way, the water cycle ( change / changes ) salt water in the oceans
into fresh water every day.

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