疑問詞 + to 不定式

疑問詞 + to + 動詞原形 就像句子裡的一個小問句：what to do = what I should do，where to go = where I should go。它常放在 know、decide、learn、remember、ask、explain、tell、show… 後面。

💡中文說“不知道說什麼”，疑問詞後面直接跟動詞，所以學習者常常漏掉 to（不說：I don't know what say）。記住：疑問詞 + to + 動詞。

1. 說自己不知道或不確定該做什麼

• We're lost. We don't know which way to go.

  我們迷路了。我們不知道該往哪邊走。

• I'm not sure what to wear to the interview.

  我不確定面試該穿什麼。

2. 禮貌地問路或詢問做法

• Excuse me, can you tell me how to get to the bus station?

  打擾一下，能告訴我怎麼去汽車站嗎？

• Do you know where to park around here?

  你知道這附近哪裡可以停車嗎？

3. 學習、教或演示怎樣做某事——learn / teach / show + how to

• I learned how to swim when I was six.

  我六歲的時候學會了游泳。

• Can you show me how to use this machine?

  你能教我怎麼用這臺機器嗎？

4. 決定、記得、忘記——decide / remember / forget + 疑問詞 + to

• Have you decided where to go for your holiday?

  你決定好假期去哪兒了嗎？

• I always forget how to spell “necessary”.

  我總是忘記 “necessary” 怎麼拼。

和 tell、show、teach、ask 連用時，人緊跟在動詞後面，放在疑問詞之前。Explain 不一樣：要說 explain to me how to…，或者不提人：explain how to…

• She showed me how to fold a paper crane.

  她教我怎麼摺紙鶴。

• Could you explain to me what to do next?

  你能給我解釋一下接下來該做什麼嗎？（不說：explain me）

• Nobody told us when to start.

  沒人告訴我們什麼時候開始。

疑問詞 + to 不定式表示某人應該 / 可以做什麼，做這件事的人就是主語（或句中提到的那個人）。要談論別人或一個事實，就用陳述語序的完整從句。

• why 一般不這樣用：I don't know why I should go（不說：why to go）。
• to 不定式前面用 whether，不用 if：I'm not sure whether to call him.
• 在 learn 後面，how 可有可無：learn to swim = learn how to swim。
• 這個句型也可以放在形容詞和名詞後面：I'm not sure what to do. · I have no idea where to start.

• ✗I don't know what should I say.

  ✓I don't know what to say.

  用 what to + 動詞（或者用陳述語序 what I should say）。

• ✗Can you tell me how to getting to the station?

  ✓Can you tell me how to get to the station?

  to 後面用動詞原形。

• ✗We didn't know where go next.

  ✓We didn't know where to go next.

  不要漏掉 to。

• ✗I'm not sure if to call him.

  ✓I'm not sure whether to call him.

  to 不定式前面用 whether，不用 if。

• ✗Please tell me where should I wait.

  ✓Please tell me where to wait.

  句子裡面的問句不用疑問語序。

• ✗Can you explain me how to use it?

  ✓Can you explain to me how to use it?

  explain to + 人。