it will surely broaden our horizons as well as fuel our interest in learning this amazing language.
Not in this sentence. There is no infinitive.
It will broaden. It will fuel. It will broaden as well as fuel.
You must keep the two parts parallel.
It is the path to broadening our horizons as well as fuelting our interesting. -- This would work.
(Note that fueling has only one L.)
Interesting. Thank you very much for your reply. But my opionion is different.
In
The Cassell Guide to Common Errors in English, Mr Harry Blamiers says that the two verbs in such a sentence must be parallel, but this can only be regarded as his biased opinion; further, AS WELL AS can function as a preposition in this case, so it is absolutely correct to use the -ing form. Another thing you have mentioned is NO INFINITIVE, but an infinitive can be a bare infinitive or a to-infinitive. In the OALD 8th, SHE CAN SWIM is an example of the bare infinitive; that is to say, even when the auxiliary verb is WILL, it is still an infinitive.
Another important thing to mention is you tell me to 'note that fueling has only one L'; thank you very much for your reminder. But before your reminding anyone, I advise you to read the OALD first:
http://oald8.oxfordlearnersdictionaries.com/dictionary/fuel_2
I hope that no one will say the OALD is wrong in recording the -ing form of FUEL in British English.