Yes, it is grammatically correct to use the future tense and present continuous tense after "when" in a sentence. The use of these tenses depends on the context and the timing of the actions or events you are describing. For example: Future Tense: "When I finish my work, I will go to the gym." "We'll call you when we arrive." Present Continuous Tense: "When she is studying, she prefers to listen to music." "I'll come over when they are playing video games." In these examples, "when" is used to introduce a specific time or condition, and the verbs that follow can be in the future tense or present continuous tense based on the intended meaning.