Answer:
Avoiding an encounter with a polar bear may be as simple as staying alert and being prepared.
or
If people prepare properly, bear attacks are impossible.
9 gives info that the author is giving evidence about the topic
10 needs info to inform the readers
'Water freezes at 0 degrees C' is a universal truth, meaning that it is a statement accepted as a general truth.
In making this statement negative, we could say that:
<em>Water doesn't freeze at 100 degrees C. Water freezes at 0 degrees C.</em>
Or, the verb 'freezes' could be replaced by the negative form of its antonym which is 'boils'.
<em>Water doesn't boil at 0 degrees C. Water boils at 100 degrees C.</em>