if

1. Countable(可數名詞)Usually singular(通常單數)

   something that is uncertain or has not been decided yet

   不確定因素；未決之事；疑問

   • Whether this project will be realized remains a significant uncertainty.

     這個項目是否會實現仍然是一個重大的不確定因素。

condition(條件)

1. A2

   used to indicate that a particular event or action will occur only after another event or action has taken place or becomes true

   假如；如果

   • I will give you double pay if you can finish this task by Friday.

     如果你能在週五之前完成這項任務，我會給你雙倍工資。

   • We will host the party in the garden, if the weather is nice. Otherwise, it will be held indoors.

     如果天氣好，我們會在花園裡舉辦派對。否則，派對將在室內舉行。

   • If anyone calls, please inform them that I will be back in the office at four o'clock.

     如果有人打電話來，請告訴他們我四點會回到辦公室。

   More examples

contrast(對比)

1. although

   雖然；即使

   • Even though they ask for a lot, they are really great kids.

     即使他們要求很多，他們真的是很棒的孩子。

   • Although it was windy, it was still very hot that day.

     雖然風很大，那天還是很熱。

frequency(頻率)

1. B1

   every time

   每當；當

   • Water turns into steam if heated to 100 degrees Celsius.

     水如果加熱到攝氏100度就會變成蒸汽。

   • I experience a headache if I don’t get adequate sleep.

     如果睡眠不足，我就會頭痛。

assumption(假設)

1. used to mean "if it is true that"

   如果

   • I sincerely apologize if I have offended you.

     如果我冒犯了您，我誠摯地道歉。

possibility(可能性)

1. B1

   used to introduce a clause, often in indirect speech, that shows two or more possibilities

   （用於引導從句，常為間接引語）是否

   • Mrs. Kramer called half an hour ago to inquire if her cake was ready.

     Kramer太太半小時前打電話來詢問她的蛋糕是否準備好了。

   • I do not care if he approves or not—I am coming regardless!

     我不在乎他是否同意——無論如何我都要來！

   • I was wondering if you would like to join me for a movie tonight?

     我在想你是否願意今晚和我一起看電影？

politeness(禮貌)

1. used when you want to make a polite request or remark

   （用於禮貌地提出請求或評論）

   • If you'd like to take a seat, Mr. Zhang will be with you shortly.

     如果您願意就座，張先生很快就會來見您。

   • Would you mind if I opened the window?

     您介意我開窗嗎？

   • There are, if I may say so, a couple of issues with this plan.

     如果我這麼說，這個計劃有幾個問題。