5 exercises — practise negating necessity precisely in technical specifications.
0 / 5 completed
1 / 5
Which sentence correctly states that an action is optional (not required), rather than forbidden?
"Clients don't need to send an Accept header; the server assumes JSON either way" correctly expresses absence of obligation: the header is optional, not forbidden. Option A's "mustn't" incorrectly states the header is prohibited, which contradicts the intended meaning that it is simply unnecessary. Option C incorrectly adds "to" after the modal "needn't", which takes a bare infinitive, not "to + infinitive". Option D stacks two negatives in a non-standard way that does not clearly express optionality.
2 / 5
Which sentence correctly uses "must not" to state a genuine prohibition in a security specification?
"Log entries must not include raw passwords or API keys" is correct for a genuine prohibition — this is a hard rule, not something merely optional. Options A and B both express absence of obligation ("it's fine either way"), which understates a security requirement that should be treated as forbidden. Option D combines two modal negations in an ungrammatical way that does not clearly express prohibition.
3 / 5
Which sentence correctly uses "need not" in a more formal register, matching RFC-style requirement language?
"Implementations need not support the deprecated v1 handshake" is correct: formal "need not" behaves as a modal auxiliary, taking the bare infinitive directly, and correctly expresses that support is optional, not required. Option B incorrectly adds "to" after "need not". Option C contradicts itself by combining "must not" (prohibition) with "but may" (permission) in the same clause. Option D uses the contracted spoken form "needn't" incorrectly with a gerund instead of the bare infinitive.
4 / 5
Which sentence correctly distinguishes optional retry behavior from a prohibited one using both modal forms accurately?
"Callers needn't retry on a 200 response, but they must not retry on a 400 response" correctly uses "needn't" for the genuinely optional case (retrying on success is simply unnecessary) and "must not" for the genuinely forbidden case (retrying on a client error is a real anti-pattern). Option B swaps the two situations, incorrectly forbidding the harmless case and merely discouraging the harmful one. Option C is missing "to" after "need" and incorrectly uses a gerund after "must not". Option D incorrectly adds "to" after both "need not" and "mustn't", which take bare infinitives.
5 / 5
Which sentence correctly uses "don't need to" (rather than "can't" or "mustn't") to describe an unnecessary manual step now that automation exists?
"Engineers don't need to restart the service manually now that the healthcheck auto-recovers it" correctly expresses that the manual step has simply become unnecessary, not that it is forbidden or impossible. Option A's "mustn't" wrongly implies the action is prohibited. Option B's "can't" wrongly implies the action is now impossible, which is a different claim from it being merely unnecessary. Option D incorrectly adds "to" after the modal "needn't".