Fill in the blank with the correct Passive Voice form. These documents ______ with a pencil.

Explanation:

The sentence requires the passive voice because the documents are not performing the action of signing; they are being signed. The modal verb 'must' indicates obligation or necessity, which fits the context of signing documents. Therefore, the correct passive construction is 'must not be signed' if the intention is to prohibit signing with a pencil, or 'must be signed' if the intention is to mandate it. Given the options and the common use of 'must' in instructions, 'must not be signed' is a plausible interpretation for a prohibition.

Options analysis:

• 'cannot sign': This is active voice and implies the documents lack the ability to sign.
• 'are not signed': This is passive voice but lacks the modal verb to express necessity or prohibition.
• 'must not be signed': This is passive voice and expresses prohibition or a strong negative obligation. This fits the context if the rule is that these documents should not be signed with a pencil.
• 'must not sign': This is active voice and implies the documents themselves have the obligation not to sign.

Based on the structure and the likely intent of the question, the passive voice construction with a modal verb expressing necessity or prohibition is required. The phrase 'with a pencil' suggests a condition or method for signing, implying a rule. If the rule is that signing with a pencil is forbidden, then 'must not be signed' is the appropriate choice.

Answer:

must not be signed