問以下兩句英文句子

(1) They believe (that) "noun-clause".

The noun-clause is in "inversion" format.

It could be viewed as: Hong Kong can be deemed (to be) a reputable member in this global community only through relentlessly reaching the apex of universal economy pyramid.
note: idiomatically, we use "to be" instead of "as" for the passive voice of "deem".

Active Voice: We can deem Hong Kong a reputable member .....
note: unlike its synonym "consider", the verb "deem" doesn't need to be followed by "as" before the object complement "a reputable member".

Structure of the above "noun-clause":
Subject: Hong Kong
Verb: can be deemed
Subject complement (modify Hong Kong): a reputable member in this global community
Adjunct (adverbial phrase): only through relentlessly reaching the apex of universal economy pyramid

2) Though Hong Kong is the hub of many cultures, it is irrational to say that their looming extinction (elimination) is set (held) at bay.
雖然香港是許多文化的樞紐，說它不會因此面臨滅絕(淘汰)未免太不理性了。

"is set at bay" can be understood as "is held at bay".

something is held/kept at bay: (it is an idiom)
meaning: something is prevented to be dangerous or unpleasant from happening or from coming too close.

2015-04-11 00:44:21 補充：
Adjunct (adverbial phrase): only (adverb) + prepositional phrase (starting with the preposition "through")

2015-04-11 06:45:00 補充：
Grammar Note:

Complement and Adjunct are two different elements in grammar. While Complement is compulsorily required to complete a meaning, Adjunct is only a piece of additional information which can be omitted.

2015-04-11 08:08:22 補充：
Grammar note (for Inversion):

There are several situations that we can construct an inverted sentence. One of them is after some negative adverbials.

Examples:
rarely, seldom, never, at no time, not only, not until, little, hardly, scarcely,
only after, only if, only + prepositional phrase

2015-04-11 08:19:03 補充：
它(們) = 這些文化 "the cultures" as in "the hub of many cultures" (它 不是指 Hong Kong)

雖然香港是許多文化的樞紐，說它們(這些文化)不會因此面臨滅絕未免太不理性了。

2015-04-11 08:48:41 補充：
S + V + O or SC, "only" + Prepositional Phrase (PP)

Inversion:

"Only" + PP, aux. or modal or LV + S + V (base form) + O or SC. (aux = do or did; LV = Linking Verb)

2015-04-11 08:52:39 補充：
例：
The teacher was able to control the class, only by threatening extreme physical violence.

Inversion:
Only by threatening extreme physical violence was (LV) the teacher able to control the class.
Only by threatening extreme physical violence could (modal) the teacher control the class.

2015-04-11 08:54:08 補充：
例：
The teacher controlled the class only by threatening extreme physical violence.

Inversion:
Only by threatening extreme physical violence did (aux) the teacher control the class.

Thanks for Duncan's input:

https://hk.knowledge.yahoo.com/question/question?qid=7015041000043

TOMING88 , please don't confuse us with your poorly presented answer with the hard to comprehend grammatically wrong expressions.
A big thank-you to you if you don't do this any more!

(1)
To subject something to close examination,we found the subjects are not "They believe" which mentioned twice.
We found another subject to close examination=HK
verb=can be deemed (to be),Not as--- as passive----no need to use some unnecessary verbs= verb"enable/let,which are errors !
Subject complement as a noun cl:-a reputable member in this global community.
another complement:-only through relentlessly reaching the apex of universal economy.
Hence:-S +v+ sc.

(2)Briefly:-
HK is the hub-------main cl
facing no extinction------negative meaning, irrational,a phrase
can face extinction-------posittive meaning, rational, a phrase.
set at bay=can face extinction;can set back, can misfortune, can obstacle, can be a problem, Not set about,Not set free, Not set off, Not depart.

2015-04-11 08:37:14 補充：
(1)Inversion=change position or order of something to its opposite=eg:-sub+v+0=HK is a reputable member---->0+s+v=A reputable member HK is.(2)facing no extinction=It's rational to say there are crisis looming...