What is the correct form of dieser for “this chair” (der Stuhl, accusative)?

Your friend asks: “Welche Sprachen sprichst du?”

Someone says “Wer ist Erika?” What are they asking?

What does “Was gibt es zu essen?” mean?

Ich komme aus Mexiko. Welche Sprache spreche ich? 

Which of the following is a polite way to thank someone?

You’re at a restaurant in Switzerland and want to confirm if they accept credit cards. What should you ask?

Which of the following means “in front of the toilets”?

You are meeting a new person and want to introduce yourself. What do you say?

What is the correct way to say “She is 81 years old” in German?