Answer:
The sea has waves. They go up and crash back down. You can think of this as hard times. When you think your doing good and start rising to the top you often crash back down. This (the crash) leads to difficulties or troubled times.
Answer: The second and third sentences are punctuated correctly.
Explanation:
The second to last is not a complete sentence and the last doesn't start with a capital letter. The first sentence is missing multiple commas.
The linking verb is 'is'. A linking verb is a verb that indicates state of being, such as 'is', 'was', and 'am'. The word 'is' in the sentence indicates that Montana exists as a state known for its beautiful recreational area, so it is the linking verb that connects Montana to the rest of the sentence.
Hope this helps!