英文問題!急急急急急！唔該！（急！關乎生死~)

1. Word order + Lack of enogh conjunction
It should be:
Factories, power plants and heavy traffic are the causes of pollutions
because they give off so much smoke.

2. Redundance
It should be:
We can donate money to the charities to help people in need.

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For Q.2, please refer to Wilson's answer.

For Q.1, it should be rephrased as:

One of the causes of air pollution is smoke emitted from factories, power plants and heavy traffic.