Using the particle 了

1. 了 that follows verbs

1.1. Difference with 过

1.2. Action verbs, e.g., 吃，看

1.2.1. Verb takes an object that includes a number phrase, e.g., 我看了三本书。

1.2.2. Indicating duration when the verb takes a time phrase, e.g., 我学了三个钟头。

1.2.3. Indicating duration when the verb takes an object and a time phrase, e.g., 我写了两个论文，写了整整三年。

1.2.4. Two or more actions occur in sequence.

1.2.4.1. If-then statement, e.g., 他吃了饭就走。

1.2.4.2. Dependent clause sets a new temporal reference, e.g., 我来中国以前，在日本住了一年。

1.2.4.3. With temporal reference firmly fixed to time of utterance, e.g., 我们吃了饭以后，就看了电影。

1.2.4.4. With temporal reference seeming to “pivot” to point in past, allowing for “narrative” quality, e.g., 我们吃了饭以后，就去看电影。

2. 了 that goes at the end of a sentence

2.1. Stative verbs, e.g., 他不开心了。

2.2. Indicating that a situation does not exist anymore, e.g., 他不吃肉了。

2.3. Pragmatic issues

2.3.1. Imminent arrival, e.g., 我们快到了。

2.3.2. Relevant changed state, e.g., 他的导师退休了。

3. Sentences that combine verbal 了 and sentence ending 了

3.1. Actions that continue into the future: double 了, e.g., 我在美国住了三年了。

3.2. Every action verb instance examined along the other node, but with the addition of a 了 as a sentence final

4. How we should think about the 了 particle and what it's actually doing

4.1. Verbal 了 indicates completion (perfectiveness) in relation to a temporal reference but is not equivalent to English Past Tense; how should we think about what this particle does?

4.2. Sentence 了 is often presented based on its many pragmatic functions, e.g., imminent arrival, relevant changed state, etc. However, is this the best way to teach this particle given that what it really only does is indicate that the sentence is to be taken as a current state? Does teaching the pragmatic reasons for emphasizing a state confuse the issue for students?