Select the most appropriate option to fill in the blank.

When are you ______ to write to your friend?

Going

The correct option to fill in the blank is going.

The sentence is in the present continuous tense, which is used to talk about actions that are happening now or in the near future. The subject "you" is singular, so the right verb is "going".

The other options are incorrect.

• Gone is the past participle of the verb "go". It is used to talk about actions that have already happened. For example, "I have gone to the store."
• Goes is the third person singular present tense of the verb "go". It is used to talk about actions that a person or thing does regularly. For example, "My dog goes to the park every day."
• Go is the infinitive form of the verb "go". It is used to talk about actions in general. For example, "I want to go to the store."