A grammar question, As or That?

Here's a sentence:" However, stress isn't the bad thing ＿＿ it is often supposed to be." Should I use "as" or "that" to fill in the blank? And how to figure out the difference?

I thing the answer should be "as' because the blank is lack of connection word.

I would prefer to use "as".  This is because you are comparing your own opinion about stress with other people's opinion. I would also prefer to say "a bad thing" instead of "the bad thing".

However, stress isn't (always/such) a bad thing as it is often supposed (/thought) to be.

http://www.britishcouncil.org/learnenglish-central-grammar-other-areas-as.htm

http://helpguide.org/mental/anxiety_types_symptoms_treatment.htm

as adverb
1. as adverb (often followed by `as') to the same degree: "they were equally beautiful"; "birds were singing and the child sang as sweetly"; "sang as sweetly as a nightingale"; (`every bit' is informal as in "he is every bit as mean as she is")
See also: equally , every bit

as conjunction
2. as conjunction 如;像; 似 (conj) in the degree, manner, etc., of or that; in the way in which.: Do it as they do.

as Coordinating conjunction
3. as Coordinating conjunction 在．．．的期間;當．．．的時候 (conj. subord) If something happens as something else happens, it happens at the same time: The play started as I got there.

as noun
4. As noun a very poisonous metallic element that has three allotropic forms; arsenic and arsenic compounds are used as herbicides and insecticides and various alloys; found in arsenopyrite and orpiment and realgar
See also: arsenic , atomic number 33

as phrasal preposition
5. as phrasal preposition 至於某人[某事物] (phr. prep) You use as for and as to at the beginning of a sentence in order to introduce a slightly different subject that is still connected to the previous one.: As for you, I never want to see you here again.
6. as phrasal preposition 一樣;一般 (phr.conj)You use the structure as..as when you are comparing things.: There was no obvious reason why this could not be as good a film as the original.

as preposition

7. as preposition 當作 (prep) in the role, function, or status of.: You have no choice but to act as our leader.

2. that is adverb that is to say; in other words
See also: i.e. , ie , id est
3. that is to say adverb as follows
See also: namely , viz. , videlicet
4. that much adverb to a certain degree: "we will be that much ahead of them"

http://vlc.polyu.edu.hk/

That or Which or Who?

Do not use which to refer to persons. Use who instead. That, though generally used to refer to things, may be used to refer to a group or class of people.
[Examples:] The player who [not that or which] made the basket at the buzzer was named MVP.
The team that scores the most points in this game will win the tournament (Hacker, A Writer's Reference 136).

我認為應該是 that 才合理。

理由如下：

the bad thing 是指已經提過的事情，所以才會用 the ；否則就應該用 a . 既然題目已經點名了這點，那後面就只能用 that 了。

因為 that 在接下去引領的形容子句 it is often supposed to be 中，原本是應該給擺在最後面的。   it is often supposed to be that. 移到子句前是作為引領並指定修飾對象。

反過來說，若是用 as ;那後面跟著的修飾子句，就變成了副詞子句。這樣一來， it is often supposed to be 就沒了對象；而變成修飾前面全句。這樣就變成前句沒有說清楚 the bad thing 到底是指什麼咚咚？

所以應該是 that .

Oh, I'm sorry that I didn't make things clear enough. Actually it is not a single sentence but from a passage. Here's part of it:" In the part few years, quite a number of men and women have chosen to do something less competitive. They are afraid that the stress and strains of work will rob them of joy and happiness and do them harm both physically and mentally. In fact, however, stress isn't the bad thing ＿ it is often supposed to be." So, there's no problem with "the".

Hi, andrewhsu. Do you mean a conjunction? If it is used as a conjunction, I think the clauses should be complete sentences, but "it is often supposed to be" is not.

Thanks for your thoughtfulness (I mean the Chinese annotations), dear tiffintime ;) I tended to use "as" at first, but later I changed my mind. My question is, if "as" is used to convey the meaning of comparison, shouldn't it be "However, stress isn't such a bad thing as it is often supposed to be"?

fathma: 你的意思是，这是个用that引导的定语从句？假如要用as且作连词，那么可否写成"Stress isn't the bad thing as it is often supposed"？(语法学得不怎么好，见谅 ;))

Thanks a lot for the detailed explanation, Messy-Gal. Still, there's something I don't completely understand. " 'That' can't be used in that sentence. If you intend to use 'that' the following sentence must have a main verb." If we use "that", isn't it an attributive clause introduced by "that"? And what's wrong with it?

I don't understand why English grammar needs to be so rigid.

hi