①when是at or during the time that, 既指時間點，也可指一段時間，while是during the time that，只指一段時間，因此when引導的時間狀語從句中的動詞可以是終止性動詞，也可以是延續性動詞，而while從句中的動詞必須是延續性動詞。
②when 說明從句的動作和主句的動作可以是同時，也可以是先後發生；while 則強調主句的動作在從句動作的發生的過程中或主從句兩個動作同時發生。
a. When the teacher came in, we were talking.
當此句改變主從句的位置時，則為：
While we were talking, the teacher came in.
b. They were singing while we were dancing.
④when和while 還可作並列連詞。when表示“在那時”；while表示“而，卻”，表對照關係。如：
a. The children were running to move the bag of rice when they heard the sound of a motor bike.
孩子們正要跑過去搬開那袋米，這時他們聽到了摩托車的聲音。
b. He is strong while his brother is weak.
他長得很結實，而他弟弟卻很瘦弱。
①when是at or during the time that, 既指時間點，也可指一段時間，while是during the time that，只指一段時間，因此when引導的時間狀語從句中的動詞可以是終止性動詞，也可以是延續性動詞，而while從句中的動詞必須是延續性動詞。
②when 說明從句的動作和主句的動作可以是同時，也可以是先後發生；while 則強調主句的動作在從句動作的發生的過程中或主從句兩個動作同時發生。
a. When the teacher came in, we were talking.
當此句改變主從句的位置時，則為：
While we were talking, the teacher came in.
b. They were singing while we were dancing.
④when和while 還可作並列連詞。when表示“在那時”；while表示“而，卻”，表對照關係。如：
a. The children were running to move the bag of rice when they heard the sound of a motor bike.
孩子們正要跑過去搬開那袋米，這時他們聽到了摩托車的聲音。
b. He is strong while his brother is weak.
他長得很結實，而他弟弟卻很瘦弱。