From the text: “Customers ordered online, chose in-store pickup, and within an hour received confirmation emails.”

→ Past Simple — narrative sequence of events

Past Simple requires parallel verb forms in a sequence. 'Demand' should be 'demanded' to match 'claimed' in the coordinated structure.

From the text: “The second buyer's recognition of the error seems more obvious, suggesting they should have realized something was amiss.”

→ Modal Perfect — retrospective obligation/criticism

Modal perfect 'should have realized' expresses criticism about a past failure to recognize something. Present forms cannot express retrospective judgment about completed situations.

From the text: “The tablets were handed over without question.”

→ Passive Voice — focusing on recipient of action

Passive requires 'be + past participle'. 'Handed over' without auxiliary 'were' is incomplete. The correct form is 'were handed over'.

From the text: “The retailer claimed the price was clearly an error—a technical glitch on their platform.”

→ Past Simple — reporting completed actions

Past Simple 'claimed' and 'was' report completed actions in a past narrative. Present Perfect and Past Continuous would incorrectly suggest ongoing relevance or background action.

From the text: “The company could have prevented the entire controversy had it identified the glitch earlier in the process.”

→ Modal Perfect — unrealized past possibility

Modal perfect 'could have prevented' is needed for unrealized past possibilities. 'Could prevent' with Present Simple incorrectly suggests current or future possibility, not a missed past opportunity.

From the text: “Consumer law experts point out that modern retail has made this question considerably harder to answer.”

→ Present Perfect — completed actions with current relevance

Present Perfect 'has made' shows that past changes in retail continue to affect the present situation. Past Simple 'made' would disconnect from current relevance; Present Continuous suggests temporary ongoing action.

From the text: “Many legal systems allow contracts to be voided if an error is both fundamental and recognizable to the other party.”

→ Passive Voice — focusing on recipient of action

Passive infinitive 'to be voided' focuses on what happens to the contracts (they are voided) rather than who voids them. Active 'to void' would require a subject performing the action.

From the text: “In some jurisdictions, courts have sided with consumers, ruling that a published price is an offer that, once accepted, creates a binding contract.”

→ Defining Relative — specifying which instances

Defining relatives for things require 'that' or 'which', not 'what'. 'What' cannot introduce a relative clause modifying 'devices'. The correct form is 'that they had purchased'.

From the text: “When they arrived at stores, payments processed smoothly.”

→ Past Simple — narrative sequence of events

Past Simple requires the past tense form. 'Complete' should be 'completed'. All verbs in a past narrative must use past forms.

From the text: “Had this occurred in the pre-digital era, the error might have been deemed immediately apparent.”

→ Modal Perfect — hypothetical past assessment

Modal perfect 'might have been deemed' expresses speculation about how something would have been judged in the past. Present forms cannot express hypothetical past assessments.

From the text: “Similar cases have played out elsewhere.”

→ Present Perfect — describing precedent cases

When discussing how past developments shape the current situation, Present Perfect is needed. 'Made' should be 'have made' to show these changes continue to affect the present landscape.

From the text: “Loyalty cardholders discovered tablet computers listed at ninety-eight percent off the regular price.”

→ Passive Voice — formal reporting of events

Past participle 'listed' functions as a reduced passive relative clause (which were listed). It focuses on the state of the tablets rather than who listed them.

From the text: “The second buyer's recognition of the error seems more obvious, suggesting they should have realized something was amiss.”

→ Modal Perfect — retrospective obligation/criticism

Modal perfect requires 'modal + have + past participle'. 'Should recognized' is missing 'have'. The correct form is 'should have recognized'.

From the text: “In some jurisdictions, courts have sided with consumers, ruling that a published price is an offer that, once accepted, creates a binding contract.”

→ Defining Relative — specifying which instances

Defining relative 'that creates' specifies which kind of offer (one that creates a contract). 'What' cannot modify 'offer'; 'it creates' would create a run-on sentence.

From the text: “Customers ordered online, chose in-store pickup, and within an hour received confirmation emails.”

→ Past Simple — narrative sequence of events

Past Simple sequences completed actions in chronological order. Present Perfect would incorrectly emphasize current relevance; Past Continuous would incorrectly present these as background actions rather than main events.