<span>If you hold your breath, <span>carbon dioxide </span></span><span>builds up in your blood
The reason for this is:
When you exhale or breathe out, you exert or let out carbon dioxide. So, if you were to hold your breath, it would build up because it is not being exerted.
Hope this helped you!
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The correct answer is D. however.
You want to show contrast between these two sentences, and the only word among these which can do that is <em>however. </em>The sentences are each other's opposites - even though there is an increase of eagles in the Southeast, there is still a decline in their numbers overall.
A subatomic particle with a positive charge is a proton
The correct plural form of echo is echos or echoes. Either way it is grammarly correct. I believe that echoes is the correct form.
echoes
