What two places in the dictionary can you find a key to diacritical markings?

This is a bit of a trick question! There isn't a single "key" to diacritical markings in a dictionary, but there are two places where you'll find information about them:

1. The front of the dictionary: Most dictionaries will have a section at the beginning explaining how to use the dictionary, including a guide to the pronunciation symbols used. This guide will likely include a table showing diacritical markings and their associated sounds.

2. The entry itself: Some dictionaries, especially those with more complex entries, will include diacritical markings directly in the word's pronunciation guide. This is especially common for words with unusual or uncommon pronunciations.

So, while there isn't a dedicated "key" to diacritical markings, the information you need is usually found in the introductory section or within the word's pronunciation guide.