Answer:
1) <em>The nicotine from the smoke reaches their brain in <u>only</u> ten seconds. </em>
Replace only with just.
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2) <em>This puts those people at risk <u>for so many things.</u></em>
The words in bold are not required
<em>(</em><em>This puts those people at risk</em><em>)</em> is more than enough
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3) <em><u>Those</u> children exposed to the smoke, and everyone else as well, are then <u>that</u> much more likely to develop asthma and other respiratory problems in their lifetime.</em>
<u>Those</u> should be replaced by <u>The</u>
<u>T</u><u>hat</u> is not needed in the sentence.
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I have made these changes based on my opinion
Happy to help
Pls mark as Brainliest