In this English cloze passage about a traveller who is haunted by his tooth brush while travelling, choose the correct option to fill in the blank so that the expression is grammatically correct and meaningful in the sentence: “I think that I have not packed it, and wake up in a cold ____________, and get out of bed and hunt for it.”

Introduction / Context:
This question is based on an English cloze passage in which a traveller describes anxiety about forgetting to pack a tooth brush. The test checks understanding of collocations, parts of speech, and natural English expressions. The sentence focuses on the phrase “wake up in a cold … and get out of bed,” which describes a fearful or anxious physical reaction. To answer correctly, you must choose the word that fits both the grammar and the usual idiomatic usage in English.

Given Data / Assumptions:

• The relevant sentence in the passage is “I think that I have not packed it, and wake up in a cold ____________, and get out of bed and hunt for it.”
• The options given are “perspire,” “perspiring,” “perspiration,” and “to perspire.”
• The blank follows the phrase “in a cold,” which usually takes a noun, not a verb.
• The speaker is describing a state or condition caused by worry or fear.

Concept / Approach:
The central ideas tested are correct word class and common idiomatic usage. After the preposition “in,” English normally uses a noun phrase. The common idiom is “in a cold sweat,” but here the parallel structure is “in a cold perspiration,” where “perspiration” functions as a noun meaning sweat. Verbs like “perspire,” “perspiring,” or “to perspire” do not fit grammatically after “in a cold,” because they would break the expected noun phrase pattern. Therefore we must choose the noun that can stand as the object of the preposition and align with the meaning of anxious sweating.

Step-by-Step Solution:
Step 1: Identify the structure “in a cold ______” and note that a noun is required after the article “a”. Step 2: Check each option. “Perspire” is a base form verb, so it cannot follow “a” directly. Step 3: “Perspiring” is a present participle; it also cannot follow “a” to form a standard noun phrase here. Step 4: “To perspire” is an infinitive and does not fit the pattern after “a cold”. Step 5: “Perspiration” is a noun meaning sweat and correctly completes the phrase “in a cold perspiration”. Step 6: Confirm that the meaning matches the context of nervousness and anxiety about forgetting the tooth brush.

Verification / Alternative check:
You can verify the answer by replacing the blank with each option and reading the sentence aloud. Only “in a cold perspiration” sounds grammatically complete and natural. The other forms produce ungrammatical or awkward sequences such as “in a cold perspire” or “in a cold to perspire,” which are not standard English. In addition, dictionaries and usage examples confirm that “perspiration” is a noun and can be used to describe physical sweat that appears because of fear, stress, or illness. This matches the emotional state described in the passage, where the narrator is worried about having forgotten something important.

Why Other Options Are Wrong:
“Perspire” is a verb and cannot directly follow “a” in this context, so it is grammatically incorrect. “Perspiring” is a participle form used to describe a person who is sweating, not an abstract noun phrase after “a”. “To perspire” is an infinitive and does not fit the fixed expression “in a cold …”. It would also break the smooth flow of the sentence.

Common Pitfalls:
A common mistake is to ignore the small but important clue provided by the article “a.” Many learners choose forms that express the right general idea but belong to the wrong grammatical category. Another pitfall is thinking only of meaning and not of collocation, that is, which words usually appear together in English. It is also easy to be tempted by “perspiring” because it sounds similar to “perspiration,” but exam questions often use this similarity to test careful reading. Always check whether the blank requires a noun, verb, adjective, or some other form, and confirm that the option works in both grammar and natural usage.

Final Answer:
The phrase that correctly completes the sentence is “perspiration”, giving the expression “wake up in a cold perspiration”.