Learn Turkish: Seçici çocuklar sarımsak yemezdi. - Picky children didn't use to eat garlic.

It combines the verb root ye- (eat), the aorist negative suffix -mez (used for general or habitual negative statements), and the past tense suffix -di. When you combine the aorist negative with the past tense (-mezdi or -mazdı), it creates the habitual past negative. This translates perfectly to "didn't use to" or "wouldn't" (for past habits) in English.

Why isn't sarımsak in the accusative case (as sarımsağı)?

Because it refers to garlic in a general sense, not a specific piece or batch of garlic. In Turkish, when a direct object is general (meaning "garlic" rather than "the garlic"), it doesn't take the accusative case suffix. Instead, it stays in its plain dictionary form and sits directly in front of the verb.

How is the word seçici formed to mean "picky"?

It is built from the verb root seç-, which means "to choose" or "to pick." The suffix -ici (which follows 4-way vowel harmony as -ıcı/ici/ucu/ücü) is attached to verbs to create an adjective or noun describing someone who regularly performs that action. So, someone who habitually chooses is seçici (picky or selective).

Since çocuklar (children) is plural, why doesn't the verb have a plural suffix like yemezlerdi?