完成式不是「文法比較難」——是「台灣考生最常用錯」。以下兩句哪個對？
(a) I studied English for ten years. (b) I have studied English for ten years.
答案：兩個都對，意思不同。
- (a)：我學了十年，現在已經不學了（過去的完成動作）。
- (b)：我學了十年，現在還在學（延續到現在）。
IELTS 考的就是「你知不知道這個差別」。弄錯 = 時態混亂 = Grammar Accuracy 扣分。
三種完成式決策樹
你要描述的是？
├─ 從過去延續到現在，或跟「現在」有關 → 現在完成式 (have/has + 過去分詞)
├─ 過去的過去，在另一個過去動作之前 → 過去完成式 (had + 過去分詞)
└─ 未來某時間點「之前」就已完成 → 未來完成式 (will have + 過去分詞)現在完成式（Present Perfect）
have / has + 過去分詞用法 1：未完結時間（unfinished time）
事件或狀態從過去延續到現在，還沒結束。時間標記：since, for, so far, this year, this decade, recently, in recent years, over the past X years。
Global literacy rates have risen sharply since 1990.（從 1990 到現在還在變） Taiwan has experienced rapid urbanisation over the past three decades. Smartphone ownership has increased fivefold in this century. Researchers have investigated this phenomenon for over twenty years.
用法 2：新近過去（recent past）with impact on now
事件發生於不久前，且對現在有影響。時間標記：recently, just, already, lately, in recent years。
The government has just announced fresh environmental legislation. Several studies have recently confirmed the link between diet and cognition. AI tools have transformed how students approach research.
差別：Yesterday I visited the museum.（過去簡單——昨天的事，結束了） I have visited the museum.（現在完成——經驗，到現在為止曾經去過）
過去完成式（Past Perfect）
had + 過去分詞用法：表示「過去的過去」
當你在描述過去，還有一個事件發生在更早——用過去完成式區分先後。
By the time the reform was introduced, the damage had already been done. The company had struggled for years before it went bankrupt. When regulators acted, the practice had already become widespread.
時間標記：by the time, before, after, when（強調先後時），already, just, never...before。
Task 2 使用時機
Before social media had achieved widespread penetration, political polarisation was markedly less acute.
Renewable-energy costs had fallen by 90% before governments began large-scale investment.
未來完成式（Future Perfect）
will have + 過去分詞用法：某時間點之前就已完成
By 2030, global emissions will have fallen only marginally at current rates. By the end of this decade, China will have overtaken the US in total solar capacity. In ten years, most clerical jobs will have been automated.
時間標記：by [future time], by the end of X, within X years。
Task 1 圖表未來預測特別常用
According to the projection, Taipei's population will have shrunk by 8% by 2050. By 2035, global renewable capacity will have tripled.
現在完成進行式（Bonus: 延伸到現在且仍在進行）
have / has + been + -ing強調「持續」而非「完成」。
Researchers have been investigating this phenomenon for two decades.（仍在研究） Temperatures have been rising at 0.02°C per year.（仍在上升）
現在簡單 vs 過去簡單 vs 現在完成——對照
| 情境 | 句型 | 範例 | |-------------------------------|-------------------|------------------------------------------------------| | 常規事實 | 現在簡單 | Water boils at 100°C. | | 明確過去時間的單次事件 | 過去簡單 | Taiwan abolished martial law in 1987. | | 過去延續到現在 | 現在完成 | Taiwan has enjoyed democracy since 1996. | | 過去在某過去點之前 | 過去完成 | By 1987, the country had experienced decades of authoritarian rule. | | 未來某點前完成 | 未來完成 | By 2030, the population will have aged dramatically. |
Task 2 Band 7+ 句型模板
模板 1：長期趨勢（現在完成）
Over the past three decades, X has [verb-ed] markedly, driven by [原因]. Since the 1990s, Y has [verb-ed] at an unprecedented rate.
模板 2：近期變化（現在完成）
In recent years, X has [verb-ed], fundamentally reshaping [領域]. Recent research has [verb-ed] that [發現].
模板 3：未來預測（未來完成）
By [未來年份], X will have [verb-ed], with profound consequences for [領域].
模板 4：歷史反思（過去完成）
Before [過去事件], X had [verb-ed], setting the stage for [後續發展].
3 個台灣考生最常見錯誤
錯誤 1：現在完成 vs 過去簡單搞混
❌ I have visited Japan last summer. ✓ I visited Japan last summer.（有明確過去時間——用過去簡單） ✓ I have visited Japan twice.（經驗、沒明確時間——用現在完成）
規則：出現明確過去時間詞（yesterday, last week, in 2010, two years ago）不能用現在完成——用過去簡單。
錯誤 2：過去完成沒用
❌ By 2015, emissions fell by 10%. ✓ By 2015, emissions had fallen by 10%.
規則：by + 過去時間點 描述該點之前完成的動作——用過去完成。
錯誤 3：未來完成當未來簡單用
❌ By 2030, the population will age dramatically.（怪——不是在 2030 才開始變老） ✓ By 2030, the population will have aged dramatically.（到 2030 為止已變老——這才對）
10 題自測
選出正確時態。
- Taiwan (abolished / has abolished) martial law in 1987.
- Global temperatures (rose / have risen) by 1.1°C since pre-industrial times.
- By the time the new law (took effect / had taken effect), the industry already (adapted / had adapted).
- Scientists (have investigated / investigated) this issue for more than two decades.
- Last year, the government (introduced / has introduced) fresh regulations.
- By 2040, most coastal cities (will face / will have faced) significant flood risk.
- In recent years, AI (has transformed / transformed) several professional fields.
- Before the pandemic (arrived / had arrived), few companies (considered / had considered) remote work viable.
- The company (announced / has announced) its results yesterday.
- By the end of this decade, solar costs (will fall / will have fallen) below coal.
解答
- Taiwan abolished martial law in 1987.（明確過去時間）
- Global temperatures have risen by 1.1°C since pre-industrial times.（since + 延續至今）
- By the time the new law took effect, the industry had already adapted.（過去先後）
- Scientists have investigated this issue for more than two decades.（延續至今）
- Last year, the government introduced fresh regulations.（明確過去時間）
- By 2040, most coastal cities will have faced significant flood risk.（未來完成）
- In recent years, AI has transformed several professional fields.（in recent years）
- Before the pandemic arrived, few companies had considered remote work viable.（過去先後）
- The company announced its results yesterday.（明確過去）
- By the end of this decade, solar costs will have fallen below coal.（未來完成）
延伸閱讀：