Re: English grammar stuff,,,would pls answer this?
Gramatically the "it" refers to thin, runny glue (which is a bit redundant in itself, actually), but since superglue=thin glue in the sentence, semantically it makes no difference.
I would have used "that" instead of which because it is restrictive. I realize most people these days use "which" for either, but the comma would be incorrect since it does need to be restrictive and the comma would make it non-restrictive.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.