eng questionsssssssssssss

The sentence is grammatically correct.

Structure: 1st main clause, but (coordinating conjunction) + 2nd main clause

The 1st main clause tells us a fact. (By 1003 they have developed the first known gun)
"but" gives a sense of contrary.
The 2nd main clause relates to the reason behind the fact, and suggests two possibilities of the cause which is still unknown.

(1) 1st possibility = they did this because they had invented the explosive mixture to go with it
(2) 2nd possibility = they simply borrowed it from someone else

We use the conjunction "whether ... or ..." to express a choice between the two possibilities, which in a way, forms an indirect question. That means the clause "whether (1) or (2)" functions as a noun clause (interrogative content clause), being the subject of the 2nd main clause.

You would perhaps see it clearer if I put the sentence in the it-cleft structure, as follows:

..., but it is still a mystery whether they did this because they had invented the explosive mixture to go with it or (whether they) simply borrowed it from someone else.

2012-08-13 16:09:14 補充：
In fact, the 2nd possibility is only a satire to mean they have not actually developed the gun.

AnsD with China analysis,not yours;
Response:-
1003 asked them whether they(subject)had invented (verb) it all themselves or(conjunction) whether someone (else) had lent (2nd verb) them is still a mystery.

whether they(subject)
had invented (verb)
it all themselves
or (conjunction)
whether someone (else)
had lent(2nd verb)
them
is still a mystery.

Whether or not HK students're successful, China can be sure that China did her best!-----(as an eg.)

Answer: D (Not A)

if: used to introduce one of two or more possibilities (是否)

whether : used to show that sth is true either of two cases. (不管...還是...)


"whether they did this because they had invented the explosive mixture to go with it or simply borrowed it from someone else is still a mystery" as a noun phrase.

For example, the sentence is wrong is wrong.

"the sentence is wrong"as a noun phrase.

2012-08-12 19:09:02 補充：
The EXAM is likely to admire the country aged China...