of fuel\of the fuel

[coelacanth]

Hello, guys,
here is a text from an english practice book:

"Many cars have a fuel warning light. When the level of fuel in the tank is very low, this light switches on.
...
When the level of the fuel falls, the float moves downwards."

Why is there a difinite article in the second sentence?

 

[jutfrank]

You're right to wonder about this. An indefinite article would work better in this case if the idea of 'float' has not been previously mentioned.

If it has not been previously mentioned, we could assume that the writer either believes that the idea of 'float' is implicit in our conception of a fuel gauge, or that it is simply careless writing.


Edit: Apologies -- I misread the question. I was talking about the use of "the float".

 

[jutfrank]

There is no need for the before fuel and so the phrase is better without it, as in the first instance of the phrase.

the level of fuel

 

[coelacanth]

So, what is the rule for that?

 

[jutfrank]

When speaking generally, use either an indefinite or zero article, depending on whether the noun is being used countably or uncountably.

Cars need fuel.