Which word is the linking verb
when i taste something spicy, i fell uncomfortable

We can observe that the sentence structure of this statement is in passive form. The active form is the most easiest way and another method to identify linking verbs with ease. Hence, the sentence would be like:
1.      I felt uncomfortable when I taste something spicy.
Evidently, if we analyse the sentence structure in this form we can observe that “when” here is used as a linking verb. Linking verbs are connecting words that combine a subject and a predicate. Includes such as is, are, was, were and verbs.

Afirefighter is a rescuer extensively trained in firefighting, primarily to extinguish hazardous fires that threaten life, property and the environment as well as to rescue people and animals from dangerous situations.  just cut some parts to make them shorter and add some of your facts or what describes them most. or what they are supposed to do.