Other productive usesNouns are preceded by the determiner the in several other contexts.
1 Nouns which refer to parts of the body are preceded by the in medical contexts.
Most of the alcohol you drink is rapidly absorbed into the bloodstream.
Children with the defective gene lack a particular protein which produces enzymes necessary to balance chemicals in the brain.
2 Nouns which are being used in the singular to refer to a particular kind of animal or thing are preceded by the.
The hibiscus beetle is black and just a few millimetres long.
Since the invention of the steam engine, luxury trains have for ever inspired fantasies of romance and adventure.
3 Sometimes there is only ever one thing of a particular kind in a place, or a vehicle or machine only ever has one part of a particular kind. Nouns which refer to these things or parts are often preceded by the.
My daughter can barely even see the whiteboard from where she sits at the back of the class.
Within moments of the curtain rising, Prokofiev's heroine tells all in a narration that sets the dramatic tone for the entire opera.
A free kick 10 minutes later found the defender, whose header sailed into the net.
No, it wasn't a taxi, it was a private car with a bearded man at the wheel.
4 Nouns which refer to qualities or abilities that are needed to do something often occur in the pattern the N to-inf: see Section 21, Other related patterns. They sometimes also occur preceded by the, but not followed by a to-infinitive.
Most would have liked to have acted professionally, but admit that they never had either the opportunity or the nerve.