[ti:How to Use ‘When’ and ‘While’] [by:www.51voa.com] [00:00.00]更多听力请访问51VOA.COM [00:02.12]Tony from China writes, [00:04.16]Hi! I am an English learner from China. [00:07.40]I want to know the difference between when and while. [00:11.16]Thanks! Tony, China. [00:13.24]Dear Tony, [00:14.76]This is a very interesting question, [00:17.12]because both words [00:18.48]are what grammar experts call "subordinating conjunctions." [00:23.32]That means we use them to connect subordinating clauses [00:27.40]to the main clause of a sentence. [00:30.68]A subordinating clause is a part of a sentence [00:34.16]that adds additional information to the main clause. [00:38.68]Here is an example: [00:40.80]I read Tony's email when I started work today. [00:45.72]The main clause is "I read Tony's email." [00:49.28]The additional information is "when I started work today." [00:55.04]The subordinating conjunction "when" tells us that the time of the second event [01:00.64]was almost at the same time or very close to the time of the first event. [01:07.44]Note that both these actions – "start" and "read" [01:11.48]are single actions, using verbs in the simple past tense. [01:17.68]That is an important thing to remember [01:20.12]as we look for the difference between "when" and "while." [01:24.36]Now, look at this example: [01:26.80]While I was making lunch, the phone rang. [01:31.76]Here, the first action is in the present continuous tense. [01:36.36]That means the action, making lunch, took place over a period of time. [01:42.64]The main clause, "the phone rang" is in the simple past tense, [01:47.44]and it is a single action taking place at a point in time. [01:53.36]The order of the events in a sentence with subordinating conjunctions [01:57.44]can affect the choice of "when" or "while. [02:01.32]If we change the order of our example above, we get: [02:06.00]When the phone rang, I was making lunch. [02:09.64]Here, the conjunction "when" [02:12.36]is in the clause with the single action, "the phone rang." [02:17.04]So as a general rule, you should use "while" in a clause with a continuous action, [02:22.84]using a verb in a continuous tense. [02:26.96]Use "when" in a clause with a single action, [02:30.52]using a simple past or present tense. [02:34.72]If you have a question for our staff of teachers, [02:38.44]send it by email to learningenglish@voanews.com. [02:44.96]And that's Ask a Teacher! [02:46.92]I'm Jill Robbins. 更多听力请访问51VOA.COM