How to talk about "under certain conditions"

[Jonny Wang]

I'd like to be able to talk about dependent conditions and I want to confirm that I have my grammar correct. Following are a couple of examples and my own translation based on talking with a Chinese employee. Do I have it right?

1. Do you know what the volume flow is for a given vacuum level?

1a. 你是否知道在一定的真空量下流量多少？

1b. 你是否知道当一定的真空量时流量多少？

Okay, maybe one example is enough for now.

Any criticism would be appreciated.

[semantic nuance]

I'll pick 1a. But I'll change it a little bit: 你知道在一定的真空量下流量是多少嗎?

Hope it helps!

[heifeng]

My guess would be more of this format:

您知道在某某个(假定or maybe特定)条件下xx的(体积)流量为(or有)多少[insert units here](吗)?*

xx= are you talking vacuum pumps here? if so, then I'd put 真空泵 there...

*Disclaimer, this is all only a guess...

[HashiriKata]

I think I know why Johnny missed out the word 吗 (and Heifeng made it optional !) after 多少.

I think the question would be easier to understand if 吗 is brought closer to 知道:

在一定 [.....] 多少,你知道吗?

[heifeng]

Yeah, on second thought I make my 吗 non-optional...but think that HashiriKata's recommendation to put the 'do you know' part together makes the sentence sound better, or at least clearer:wink:

[gougou]

I think I know why Johnny missed out the word 吗

He didn't miss out on it though. He used the 是否 construction, which works similar to other positive-negative constructions, such as 是不是。

[HashiriKata]

He didn't miss out on it though.

And I also know that Gougou mixed up 2 things together!

(It may help if you try considering this sentence: 你知道他是否知道了吗？)

[gougou]

So you can't use it for this question?

What about this usage then, or this? How do they differ?

[HashiriKata]

What about this usage then, or this?

Things seem to be getting a bit too complicated now, let's get back to the beginning: yes, Johnny's use of 是否 was ok but his sentence was not ok. Once it has been corrected by semantic nuance and heifeng, 吗 then becomes necessary. I should have made this clearer earlier.

By the way, 是否 doesn't have problems to co-occur with 吗 (just as in my earlier example: 你知道他是否知道了吗?) or to go without: 你是否知道他知道了？(but the 2 sentences obviously don't mean the same thing.)

[semantic nuance]

你知道....嗎?: it implies the asker does not know if you know something or not.

你知道....?: it implies that the asker suspects that you've already known something but he/she is not sure of it?

Ex: 1 你知道他來了嗎?

2 你知道他來了?

When 是否 is used, that is a similar concept like in English-- "or''. When you ask: Do you want coffee or tea? (It's a question of choice). The Chinese translation goes without 嗎: 你想要咖啡還是茶?

If you ask: Do you want coffee? Then 嗎 will be added in Chinese translation: 你想要咖啡嗎? That's why 你是否知道.....?goes without 嗎.

你是否知道 is used more in written form. You can also rewrite the sentence as 你知不知道......?(also without 嗎). which is colloquial. However, you can add 呢 at the end of the sentence, and the meaning of the sentence won't change.

Ex : 你是否知道這樣做很傷人(呢)?

你知不知道這樣做很傷人(呢)?

Last, I'll list example sentences for you guys to understand.

1. 你知道他愛她嗎? Do you know he loves her?

2. 你知道他愛她? You know he loves her?

3. 你是否知道他愛她(呢)? Do you know or not that he loves her?

4. 你知不知道他愛她(呢)? Do you know or not that he loves her?

Hope it helps!

[Jonny Wang]

Thanks for all the replies. Didn't really mean to get everyone hung up on 是否 though.

My main question is on use of X 下 or 当 X 时 constructions to talk about result y occuring under condition X. My understanding is that both constructions are equivalent in meaning, with maybe different levels of formality?

I'm just wondering if my implementation of the constructions is correct or not.

[HashiriKata]

I'm just wondering if my implementation of the constructions is correct or not.

Your X 下 construction is fine for that part but your 当 X 时 is not. In 当 X 时, X in most cases needs to be a verb/adjective or a clause.

Example:

当有人需要救助时，行动胜于言语。

(= When people are in need of help, actions are better than words)

当我们赶到时，汽车早已开走了。

（= When we arrived, the bus had already left.）

[Jonny Wang]

HashiriKata,

Cool! I see what you mean. So, if I wrote it this way it should be okay, right:

你是否知道当得到一定的真空时流量多少？