Sentence Completion Explanation

The question requires selecting the correct conjunction to complete the sentence: "I will not pay for the goods __________." The sentence expresses a condition under which payment will be withheld.

Grammar Analysis: Conjunction Choice

We need to analyze the meaning and grammatical function of the provided options, specifically the conjunctions:

• Options 1 & 2: 'till'/'until' These conjunctions indicate time. Using them would mean "I will not pay until he sends me the bill again," implying payment might eventually happen after the bill is resent. This doesn't perfectly match the intended meaning of refusal contingent on the bill's resending.
• Option 3: 'if' Using 'if' would result in "I will not pay if he sends me the bill again." This implies that sending the bill is a condition that *prevents* payment, which is illogical. It suggests that if the bill is sent, payment is *less* likely.
• Option 4: 'unless' The conjunction 'unless' means 'except if'. The sentence "I will not pay for the goods unless he sends me the bill again" correctly conveys that payment will be withheld *except* in the specific condition that the bill is resent. This is the logical and grammatically correct choice.

Therefore, 'unless' is the most appropriate conjunction to complete the sentence, establishing the condition for non-payment.