Questions & Answers about Doktor soruyu cevapladı ve gülümsedi.
Why does one verb end in -dı and the other in -di?
Both are in the past tense. In Turkish, the past tense suffix changes to match the last vowel of the verb root (vowel harmony). The root of "answered" is cevapla, which ends in "a", so it takes -dı. The root of "smiled" is gülümse, which ends in "e", so it takes -di. Since it is "the doctor" (third person singular), we do not need to add any personal ending after the past tense suffix.
Why is there a -yu at the end of soruyu?
Soru means "question". Here, it is the specific object receiving the action of the verb (what did the doctor answer? The question). This means it needs the accusative case ending. Because soru ends in a vowel, we use the buffer letter y before adding the accusative suffix -u, giving us soruyu.
Is the verb cevapladı related to the noun cevap (answer)?
Exactly! Cevap is the noun form. Turkish frequently creates verbs from nouns by adding -la or -le. Here, cevap becomes cevaplamak (to answer). To say "answered", we drop the -mak and add the past tense suffix -dı.
Is gülümsedi related to gülmek (to laugh)?