Uses of 正好 / zhènghăo So, my focus today is the use of 正好, but it usage seems a little muddled.

The first usage, as an adjective is quite clear:


Just right (not too big, nor small; not too hot, nor cold etc). 这个饭不太辣不太淡 - 这个饭正好。


But then, when it is used as an adverb, things seem to get murky. I have found a number of meanings:


Coincidence. 我妹妹出生那天，正好下雪，所以爸爸妈妈叫他 小学
最好 / at best. 今天开会来了多少人? 正好20人 (sort of relates to meaning #1, as 19 and 21 people would be bad). This is a bit confusing though, as '来了' suggests we are talking about the past (how many people came) while the answer is almost making a suggestion (in the present/future)?
Should. 你也上超市吗? 我们正好一起去吧。Sort of relates to #3? We should go together (i.e. going alone would be bad, [and going with a huge group of people would be bad also])
At this time. 我正好没有什么人主张. Kind of like 现在?
?? 王老师来了，领正好声响. Does this come under coincidence (#1)? Or is there another meaning going on here?


[7.] On the basis of my understanding of the above, and the fact that my textbook describes 正好 as meaning 'the right time or opportunity to do something', I suggested the following example to my teacher. Imagine a friend wants you to help him organize his CD collection because it is so massive, but you are very busy. 3 weeks later, he invites you to dinner and therefore you say: 谢谢。我一定来。正好我们同时整理你的光盘! I.e. it would be the right opportunity to simultaneously sort out your CDs. But this is apparently wrong. Does anyone know why?!

Can anyone think of any other uses of 正好? Also, I have been told that all the adverbial uses are actually the same and have a unifying meaning. Does anybody have a clue how you could unify all these meanings?!
正好 is not an adjective, the same as 'just right' is not an adjective.

正 shows a foot, stopping at a line or wall. = right, proper
好 shows a woman and a son. Apparently to indicate a good life. This was before the 21st century! Today, this may not be considered the only way to fulfillment!

just = "exactly, precisely, punctually, not more than"
good = "excellent, fine; valuable; desirable, favorable, beneficial; full, entire, complete, pleasing;" 

这个饭正好
This dish is exactly fine/complete.
正好下雪
punctually favourable snow was falling
正好20人
exactly (the) desirable 20 people
我们正好一起去吧
we exactly (mutually) beneficial go together
我正好没有什么人主张
I precisely (the) desirable don't have anyone to make decisions for me 

Of course, I would not translate the Chinese into English quite like this. I just want to indicate what is going on. 

Both 正 and 好 have more than one interpretation, in English as well as in Chinese. So when you mix them, permutations of meaning arise. There is no "one size fits all".

What Dan said: 正好我们可以整理一下你的光盘。

或者： 我们正好可以同时整理你的光盘。