simple present tense and present continuous tense

old_boy   Sat May 06, 2006 4:55 pm GMT
Today's search:
"since when do you eat" has 89 possible results.
"since when have you eaten" has 19 possible results.
"since when did you eat" has 18 possible results.

According to tense-changing process, <Present Perfect + Since> has come from Simple Present:
1. I eat salad. (a present action)
2. I have eaten salad. (a past action)
BUT: If we mention a definite past time, we have to change the two tenses above:
3. I have eaten salad since 1987. (=1, a present action)
4. I ate salad last week. (=2, a past action)

Please note that Indefinite Time, like 'every day', doesn't start the tense-changing process:
a. I eat salad.
b. I eat salad every day.
== Indefinite Time doesn't change Simple Present to Present Perfect.

Asking "since when?" is an awkward moment.
-- Have we added a definite past time to the question?
-- Have we added an indefinite time to the question?
-- Have we mentioned any time at all?
It seems that people's opinions waver here. Obviously, <since when + Simple Present> is of most support. It means that, in asking "Since when?", most believe they add an indefinite time only, which doesn't change Simple Present to another tense: "Since when do you eat salad?"

Some may argue that, as they are asking of the time, they don't pre-add the time to the question. At this point, they just add "since when" to a question "Did/Do you eat salad?"
old_boy   Sun May 07, 2006 10:51 pm GMT
As I said, choosing the progressive forms is rather subjective. If you have an objective observation, you don't need to ask "since when", do you?

You wrote:
<<But you wouldn't say either 'Since when have you been eating salad/are you eating salad?' in this instance.>>

My reply: If you wouldn't, it doesn't mean I wouldn't too. If Simple Present is the most frequently used with "since when", it doesn't mean progressive forms are incorrect.
vallery   Thu Nov 02, 2006 12:57 am GMT
ee lo pade