Question

a list of tasks should always be written starting with an ___ or verb.

Explanation:

In task - list writing, especially in the context of writing (a sub - field of Arts), task lists are typically structured to be clear and action - oriented. An infinitive (formed with "to" + a verb, like "to write", "to clean") or a verb (in its base form, like "write", "clean") is used at the start of each task to show the action to be done. So the word that fits here is "infinitive".

Answer:

infinitive