改 Task 2 最常看到的扣分之一：語氣過度斷言。

❌ Social media is the main cause of teenage depression. ✅ Social media may be one of several factors contributing to teenage depression.

差別是什麼？——may 與 one of several。IELTS Task 2 要的是謹慎的學術語氣（hedging），而情態動詞（modal verbs）正是 hedging 的主引擎。

先看過 被動語態 與 條件句 的人會發現：三者搭配使用時，一個 Task 2 段落自動升到 Band 7+。

情態動詞三大功能

情態動詞不表時態——表「說話者的判斷」。三種判斷：

| 功能 | 關鍵字 | |----------------|------------------------------------------| | 確定程度 | must / will / should / may / might / could / can't | | 義務 / 許可 | must / have to / should / may / can | | 能力 / 建議 | can / could / should |

功能 1：確定程度（光譜）

把情態動詞想成一把刻度尺——從 100% 確定到 0% 可能。

| 確定度 | 正面 | 負面 | |-----------|-------------------------|-------------------------------| | 100% 確定 | is / will | is not / will not | | 95% | must | cannot / can't | | 80% | should / ought to | should not | | 50% | may | may not | | 30% | might / could | might not | | 接近 0% | cannot (possibly) | |

範例對照

This policy will succeed. → 100% 斷言，Band 5-6 This policy is likely to succeed. → 80%，Band 7 This policy may succeed under certain conditions. → 50%，Band 7+ This policy might succeed, though results so far are mixed. → 30%，Band 7+

Band 7 原則：除非你有鐵證，否則**不要用 *will / is***——用 may / might / could / is likely to。

功能 2：義務與許可

| 程度 | 情態動詞 | 例句 | |--------------|----------------------------|-------------------------------------------------------| | 強制義務 | must / have to | Students must submit essays by Friday. | | 建議義務 | should / ought to | Governments should invest more in education. | | 缺乏義務 | don't have to / need not | You don't have to attend every lecture. | | 禁止 | must not / cannot | Mobile phones must not be used during exams. | | 正式許可 | may | Candidates may bring a dictionary into the room. | | 非正式許可 | can | You can use my laptop if yours is broken. |

微妙差異：must vs have to——

  • You must finish by 5pm. = 說話者自己覺得需要
  • You have to finish by 5pm. = 外部規定要求

功能 3：能力與建議

| 情境 | 情態動詞 | 範例 | |--------------|---------------------|-------------------------------------------------------| | 現在能力 | can | I can type 80 words a minute. | | 過去能力 | could | When I was young, I could run 10km easily. | | 一次性過去能力 | was / were able to | Despite the rain, she was able to finish the race. | | 建議 | should / ought to | You should see a doctor. | | 委婉建議 | might want to | You might want to reconsider that decision. |

注意：could 表「過去能力」是「一般能夠」——單次成功要用 was/were able to。

過去情態動詞（Past Modals）

這是 Band 7+ 跟 Band 7 的分水嶺——過去情態動詞可以談過去的假設、建議、推測，幾乎所有 Task 2 的「檢討過去」段落都用得上。

| 形式 | 意思 | 例句 | |---------------------------|-------------------------------|---------------------------------------------------| | must have + p.p. | 過去強烈推測（幾乎確定） | The policy must have failed because growth fell. | | may have + p.p. | 過去可能（中等把握） | Climate factors may have contributed to the decline. | | might have + p.p. | 過去可能（較弱把握） | Alternative policies might have produced better outcomes. | | could have + p.p. | 過去「有可能」或「本來能」 | The crisis could have been avoided. | | should have + p.p. | 過去該做而沒做 | Regulators should have acted sooner. | | shouldn't have + p.p. | 過去不該做而做了 | The bank shouldn't have extended such risky loans. | | would have + p.p. | 過去會（第三條件句） | Had they reformed earlier, results would have been different. |

Task 2 反思段應用

If action had been taken in 2015, the crisis could have been mitigated and the economic cost would have been considerably lower. Policymakers should have heeded the early warnings from climate scientists; instead, they delayed until the consequences became impossible to ignore.

這一段用了 could have been, would have been, should have + 第三條件句——Band 7+ 的標準樣貌。

Task 2 hedging 模板（背下直接套）

| # | 模板 | |---|-----------------------------------------------------------------------| | 1 | This approach may prove effective, although ... | | 2 | There could be several explanations for this trend ... | | 3 | One might argue that ... | | 4 | Such a policy should, in theory, reduce ... | | 5 | Were it adopted, this measure would likely ... | | 6 | The evidence suggests that ... (避免 proves) | | 7 | It is possible that ... | | 8 | Policymakers ought to consider ... |

台灣學生常見 L1 轉移錯誤

錯誤 1：用 will 寫所有未來

❌ If governments invest more, air quality will improve.（過度斷言） ✅ If governments invest more, air quality is likely to improve.

will 在 Task 2 要節制使用——一篇 280 字最多 3 次。

錯誤 2：must 與 have to 不分

❌ Students must wear a uniform because it's the school rule. ✅ Students have to wear a uniform because it's the school rule.（外部規定）

錯誤 3：情態動詞後接錯形式

❌ We should to study harder.（should 後不接 to） ❌ He can speaks three languages.（情態動詞後接原形，不是 -s） ✅ We should study harder. / He can speak three languages.

硬規則：情態動詞（can, could, may, might, must, should, will, would）後面只接原形動詞——沒有 to、沒有 -s、沒有 -ed。

錯誤 4：Chinglish must 當「一定會」

❌ He must come tomorrow.（想說「他一定會來」） ✅ He will definitely come tomorrow. 或 He is certain to come tomorrow.

must 當推測用於現在／過去的判斷，不用於「一定會發生」的未來。

8 個 Band 7+ 示範句

  1. Urbanisation may well be the single most disruptive trend of the century.
  2. Governments should consider subsidising public transport rather than widening roads.
  3. The decline in birth rates might be attributed to a combination of economic and cultural factors.
  4. Had policymakers acted sooner, the current crisis could have been substantially less severe.
  5. Critics could argue that such reforms would disadvantage lower-income households.
  6. Taxation must not be the only tool used to address this problem; education is equally essential.
  7. Schools ought to teach financial literacy as a compulsory subject.
  8. The evidence suggests that moderate regulation may outperform outright prohibition.

10 題自測

填入最合適的情態動詞。

  1. Children under six ____ not be left unsupervised near water.
  2. You don't ____ bring your own laptop—we provide one.
  3. If she had studied harder, she ____ have passed the exam.
  4. This problem ____ be solved by throwing money at it alone.
  5. Governments ____ invest more in preventive healthcare.（建議）
  6. The streets are wet—it ____ have rained overnight.
  7. Candidates ____ bring a translation dictionary into the examination room.（正式許可）
  8. Twenty years ago, I ____ run a marathon without training; now I struggle with 5km.
  9. She wasn't at the meeting yesterday—she ____ have been ill.
  10. You ____ to see a doctor about that cough.

解答

  1. must (強制)
  2. have to (缺乏義務)
  3. would / might / could (第三條件句主句)
  4. cannot / will not (強烈否定)
  5. should / ought to (建議)
  6. must (強推測) 或 may / might (弱推測)
  7. may (正式許可)
  8. could (過去一般能力)
  9. must (強推測) 或 may / might (弱推測)
  10. ought (ought to) 或改寫成 should

自我檢查：1-2 題錯——細節疏忽；3 題以上——回去重看「確定程度光譜」跟「過去情態動詞」表。

延伸閱讀：