Answer:
The bank teller gave Kurt a look when he deposited a real check for twenty million dollars.
Step-by-step explanation:
The indefinite article a/an is used before nouns that are singular and countable, so there is no article before a noun that is plural.
If the word after a/an begins with a consonant, then we use the indefinite article a.
If the word after a/an begins with a vowel, then we use the indefinite article an.
The article relates to the first word of the phrase (if there are more than one, for example, there is an adjective before a noun), so if we had an adjective before the noun look that starts with a vowel (e.g. empty), the correct article would be an.