This sentence's meaning is confused because it uses two negative words: "isn't" and "hardly." Double negatives are grammatically incorrect in modern English and would technically yield a positive meaning, so we need to change out one of these negative words for a positive one. Since it isn't an option to change or omit "hardly," "isn't" contains the sentence's error and is the correct answer. One way to correct the sentence would be to change "isn't" to "is," yielding the sentence, "In the cities of the Pacific Northwest, like Seattle and Portland, there is hardly a single day that passes without rain."

The sentence's error is a split verb phrase. Verb phrases, like "had improved," should be kept together and not split by adverbs, like "significantly." To correct the split verb phrase, the verb and adverb should be rewritten as "had improved significantly."

The proper idiom for planning an action is planning to do something, not planning on something. Thus, the clause should be "I was planning to attend the festival with him."

This sentence uses the wrong relative pronoun after the adjective "upset." Usually, "that" is used. The corrected sentence reads, "Margo was upset that the zoo was wasting valuable resources on moving sidewalks when the lions needed a new enclosure."

"Maybe" is an adverb that means perhaps and is incorrectly used in this sentence. To correct the sentence's error, "maybe" needs to be changed to "may be."

"Amount of" refers to something that is not necessarily measured numerically, while "number of" refers to something that is measured numerically. Given that deaths incurred by drunk drivers is something that can be measured numerically, "number of" would be appropriate, not "amount of." If the sentence was "Given the disproportionate amount of heartache caused by drunk drivers . . .", the sentence would have been properly constructed because heartache generally cannot be measured numerically. 

Double negatives are grammatically incorrect in standard written English, so instead of saying "hasn't never cooked," one should say "has never cooked."

This sentence does not use the use the phrase “for the purpose of” correctly. This phrase is typically followed by a gerund, a verb that is used as a noun. The corrected sentence reads, "A fundraising campaign was started for the purpose of supporting ecological restoration projects in South America."

“To unanimously postpone” constitutes a split infinitive because the verb “to postpone” is split by the adverb. “Unanimously” should be placed elsewhere in the sentence.

The preposition “of” in the title “Statue of Liberty” does not need to be—and should not be—capitalized.