past tense forms - 了 vs 是...的

I know that both of these forms can be used to describe something that happened in the past. Using 了 to indicate a completed action: Wǒmen jīntiān zǎoshang dǎ wǎngqiú le. 我们今天早上打网球了． We played tennis this morning. Using the 是...的 construct to express past tense: wǒmen shì jīntiān zǎoshang dǎ wǎngqiú de. 我们是今天早上打网球的 ． We played tennis this morning Is there any difference in meaning? Which construct is preferred?

Well, I think I can answer part of this myself. I have learned that we can use the 是...的 construct to emphasize something that has happened in the past. Put the 是 in front of the thing you want emphasized. Basically, we are using this pattern to emphasize when, how, or where something happened in the past, or who did it. wǒmen shì *jīntiān zǎoshang* dǎ wǎngqiú de. 我们是*今天早上*打网球的 ． We played tennis *this morning*

Robert, 你好！ Let me first explain 是……的 as a structure. It is a tricky way to talk about past events in Chinese. You are right in saying that you can use this structure to emphasise certain details about an action, such as where or when it happened. 是……的 is usually used to talk about past events (note, it can be used for present as well, so don't confuse this as something that can only be used in the past). Here is a general breakdown of the structure: [subject] 是 [detail] [action] 的 Some examples: 我们是在伦敦认识的。 Wǒmen shì zài Lúndūn rènshi de. We met in London. It was in London that we met. 我是跟我哥哥一起开车去青岛的。 Wǒ shì gēn wǒ gēgē yīqǐ kaichē qù Qīngdǎo de. I drove to Qingdao with my brother. It was with my brother that I drove to Qingdao. 他们是去年搬的家。 Tāmen shì qùnián bān de jiā. They moved house last year. It was last year that they moved house. Each of the example sentences for 是……的 has been given a double translation to show how this structure draws attention to certain details of the action. Now lets look at 了. One of the uses of the particle 了 in Chinese is to mark completed aspect, which in English would be represented by the present perfect (past tense). Many learners of Chinese confuse this for 了 being about past events or the past tense. It's important to remember that this is not the case, it is simply an aspect marker that shows the changing state of something. Often times this involves the past tense, but 了 can equally be used in the present and future. My advise, however ambiguous this may seem, is to not over think it too much. Read a lot, simple books or something you are familiar with (such as Harry Potter, the ebooks are relatively easy to find online), this way you will naturally come to understand its use. Unfortunately, this is probably the most questioned idiosyncrasy in Chinese and there is still not well-put-together answer I'm afraid. Nonetheless, I hope this has helped and keep up the good work! - Lin Ping