until now

Avangi

plz excuse the French spelling

New2grammar

another joke? Please share

Tuongvan

Biogas has historically been used in internal combustion engines. However, the use has been limited to large-sized engines which use gas extracted from dumping grounds or sewage. Until now, small-sized engines using biogas were uncommon.

Why is the simple past ,not the present perfect , used here? What does 'until now' mean here when ' were common' is used? Is there any difference in meaning if ' have been common ' is used in its stead?

To me, there is no difference in meaning here. I personally prefer "have been", but I think that a case could be made for either. Compare the following:

Until last year, small-sized engines using biogas were uncommon. = they were uncommon until some point in the past, then they became more common.

In recent years, small-sized engines using biogas have been uncommon. = they were uncommon in the past and they are still uncommon.

Now, with "until now", which should we use? Is the "now" at which they became more common a point in the past, so we should use "were"? Or does "until now" extend sufficiently to the present that we should use "have been"?

Hi Avangi,

A few more musings...

To me, "until now" implies that the engines, though previously uncommon, have recently become common (or at least more common), or are about to become common very soon. Although "until now" signifies a change that happens "now", in practice it might mean that the uncommonness persists to the present moment or it might not, depending on context. For example, it could be used following an announcement that a company was planning to go into high-volume production, even though the engines had not yet been built. Or it could be used after a moderate number of these engines had been built (when the commonness of the engines is ambiguous), or after a significant number of engines had been built, with the meaning "until recently, but not any more".

To me, the indication of when the engines were/will be common/uncommon is determined (albeit slightly ambiguously) by the words "until now", and the choice of "were/have been" then just has to fit this. "Have been" seems to suit -- meaning that they were uncommon recently enough for their uncommonness to still be relevant to the present situation, possibly, but not necessarily, including the case that they are uncommon at this moment. You'd expect "were" to push us back further into the past, and suggest more strongly that they are no longer uncommon at this moment, but I don't personally get much of a sense of this because "until now" dominates. Even if that meaning is wanted, "were" still feels slightly odd to me -- it somehow seems to jar with "until now". But I'd struggle to make a case that "were" is actually wrong.

To me, the possibility that the engines were uncommon for one or a few brief periods in the past seems an unlikely one, and I agree with you that both tenses signify a continuous condition of uncommonness.

Tuongvan

To sum up, can we say  as follows?:

Until now + present perfect(continuous) : the action in the present perfect (continuous) in still continuing at the present moment .

-He is incorruptible .That 's why ,Until now ,he has been living in that rickety house (He is still living in it now )

Until now+ simple past (continuous): the action in the simple past(continuous) is not continuing at the present moment.' Until now 'in this case is similar in meaning to 'until recently'.

-He is incorruptible .That 's why ,Until now (=until recently) ,he was  still living in that rickety house (He is not  living in it now ).

I would appreciate it very much if you give your comments

In this context, "until now" strongly suggests that he has just moved, is in the process of moving, or is just about to move. So, the question is: does the choice of "was" or "has been" influence this range of possibilities? The presence or absence of "still" is another complicating factor.

I think I might have looked at this construction so much now that I no longer actually know what I think, but here's my best shot. Others may take a different view!

1. Until now, he has been living... -- allows all possibilities (just moved, moving, just about to move).

2. Until now, he has still been living... -- could allow all possibilities, the same as (1), with "still" suggesting that he stayed in the old house longer than might have been expected; or "still" could be emphasising that he is living there up to and including the present moment.

3. Until now, he was living... -- I guess this must, as you say, mean that he has already (recently) moved, but it doesn't sound quite right to me.

4. Until now, he was still living... -- same as (3), except "still" presumably must mean that he stayed in the old house longer than might have been expected (because of "was", it can't mean that he is still living there up to and including the present moment).

To me, there is an awkwardness about using "until now" with "living", which is more pronounced with versions (3) and (4). In fact, version (4) really just sounds like bad English to me.