Learn Turkish: Yasak yere girebilirler mi? - Can they enter the forbidden place?

The word breaks down into: gir- (verb root: enter) + -ebil (ability/possibility) + -ir (the aorist tense marker, which is standard with -ebil in positive statements) + -ler (they). Finally, the question particle mi is written as a separate word at the end to make it a question.

Why does yer (place) have an -e at the end?

In Turkish, the verb girmek (to enter) requires the dative case (-e/-a) on the destination to show movement into something. Because of this rule, yer becomes yere (to the place).

Why is the question particle mi used here instead of mı or mu?

The question particle always follows 4-way vowel harmony based on the word immediately preceding it. Because the final vowel in girebilirler is e, the question particle must be mi.

Is yasak a noun or an adjective in this sentence?

Here, yasak (forbidden) is acting as an adjective. It is placed directly before the noun yer (place) to create the phrase yasak yer (forbidden place).