Can, Could, Be Able To: Mistakes to Avoid for the TOEIC®

Can, could, and be able to all express ability or possibility, but they are not interchangeable.

Generally, can is used for general ability in the present, could for the past or a hypothetical possibility, and be able to replaces can in certain tenses where can is impossible (future, present perfect).

Many test-takers mistakenly choose "can" after a modal verb or in a future tense structure, when grammatically, only "be able to" works.

Can and Could: Basics Often Overlooked

-> Can expresses present ability or informal permission.

-> Could functions as the past tense of can, but also as the conditional to express a future possibility.

Essential Forms and Structures

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In Part 5, questions test a simple rule: can and could are never followed by "to." This is different from be able to.

Classic error: Writing "can to do" instead of "can do."

Common Traps with Could

Could in the past does not guarantee that the action was actually performed. Compare these two sentences:

• "I could swim when I was five."
  (General ability)
• "I was able to swim across the lake yesterday."
  (Specific achieved action)

In Part 7, if an email says, "We could deliver by Friday," it could mean "we might" (conditional) or "we were able to" (past specific action). Comprehension questions play exactly on this ambiguity.

Be Able To: An Alternative You Must Know

Be able to replaces can in all tenses where can doesn't exist grammatically. It's simple: can only has two forms (can/could), so for the future, present perfect, infinitive, or after another modal, you use be able to.

Concrete examples:

• "We will be able to process your request tomorrow."
• "She has been able to increase sales by 15%."
• "You might be able to attend the meeting."

Grammar mistakes: "We will can process" or "She has can increase."

Comparative Chart: Can/Could and Be Able To

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Based on our experience assisting candidates with the TOEIC®, the majority choose "can" everywhere, even in the future tense.

Result: A systematic error in Part 5 as soon as an auxiliary verb or future time marker appears.

TOEIC® Traps in Part 5

Grammar questions exploit three main points of confusion.

Trap 1: Modal + can

"Employees ________ be able to access the system next week."

• (A) can
• (B) will
• (C) could
• (D) should

Some may reflexively select (A) "can."

Error: "next week" requires the future tense, so the correct answer is (B) "will be able to."

If you choose "can," the sentence refers to the present, not the future.

Trap 2: Present Perfect + Ability

"Since the update, users ________ log in faster."

• (A) can
• (B) have been able to
• (C) could
• (D) are able to

"Since" signals the present perfect. Only (B) works.

(A) and (D) are simple present; (C) is past or conditional.

Trap 3: Could vs. Was able to in the Past

"The team ________ complete the project ahead of schedule."

• (A) could
• (B) was able to
• (C) can
• (D) has been able to

If the sentence refers to a specific, successfully achieved result, "was able to" is the correct answer.

"Could" only expresses a past ability without indicating whether the action was actually completed.

Checklist to Remember

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Permission, Possibility, and Politeness

Can and could are also used to ask for or grant permission. Could is more polite, but both work.

• "Can I leave early today?" (Direct)
• "Could I leave early today?" (More formal)

In TOEIC® Part 3, business conversations frequently use "could you" for polite requests between colleagues.

• "Could you send me the updated budget report?"

The response might be "Sure, I'll send it right away" or "I'm afraid I can't access it right now."

Note: "can't" expresses impossibility, not a categorical refusal.

Ready to Practice?

Mastering can, could, and be able to can easily earn you points in Part 5, provided you practice with real test traps.

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