MrPedantic said:First of all, I should qualify point 5 in my last post: you might not expect to say "I go to work by train" while on the train, but you might say "I go to work by train every day" during a discussion with a fellow traveller. So I had better withdraw that part of it.
My reply: I am afraid this is not realistic. As the late grammarian Otto Jespersen pointed out, the earth is rotating around the sun, but we say only "The earth rotates around the sun". He sensed there must be some reason to use Present Progressive. He theorized Present Progressive is used because of a contrast with other tenses. I have accepted this theory and applies it also to all kinds of tenses. I have furthered that tenses are used to tell the time relations between actions. On one-sentence basis such as your example "I go to work by train", you cannot explain any tense.
As I am living in Hong Kong, I can say I live in Hong Kong, "while in Hong Kong".
If someone asks you why you are on the train, you may of course tell him "I go to work by train", while on the train.
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MrPedantic said:Again, I'm sorry if I've misinterpreted your comment; but I would say that although we label e.g. "I go" in "I go to work by train" as "present tense" (i.e. it does not have a past tense inflection), its aspect is "habitual", i.e. it expresses a composite past-present-future context. If the speaker wanted to limit the context in some way, he would have to choose another form, e.g.
1. I used to go to work by train.
2. From now on, I'll be going to work by train.
My reply: To argue and hold that "I go" in "I go to work by train" has not a past tense inflection, is a disaster. Nothing escapes from time, and every action or habit also has its past, thus taking past tense inflection.
We have often heard that there are continuous aspect and perfective aspect, but when have they started to claim Simple Present to be an aspect? Can you quote any sources on the web that claim Simple Present is "aspect"?
As for English tense, aspect is a special word and "habitual" is not an aspect.
Don't we use also Simple Past or other tenses to say so-called habitual aspect, as in the following?
Ex: When I lived in UK, I went to work by train every day.
Ex: When I go to university next year, I will get up early every day.
Why will you repeatedly stay on "used to" alone? One habit must have its details and it is foolish to claim we can always use one sentence to encompass any habit. If a writer uses a few sentences to describe a past habit, will he use "used to" in all the sentences, as in the following?
Ex: ?"He used to sit in the balcony for the early morning. He used to enjoy the morning sun and take a cup of coffee. He used to read newspapers and listen to the radio music."
== I don't think one will describe it all the way with "used to".
Rather, Simple Past has to be used:
Ex: "He used to sit in the balcony for the early morning. He enjoyed the morning sun and took a cup of coffee. He read newspapers and listen to the radio music."
Also, is "used to" a past tense or present tense? If you recognize "used to" to be past tense, we still use past tense to say a past habit, don't we?
Or do you know we only use "used to" to express past habits?