1. I'm sorry, but I won't be able participate in the meeting next Tuesday. (не смогу - будущее время потому что next - глагол can в будущем времени - эквивалент to be able to)
2. I like this hotel room. You can see the mountains from the window. - верно
3. You are speaking very quietly. I can't hear you. - верно
4. Where is my bag? I can't find it. - верно
5. Mary got the job because she could speak five languages. - got в времени значит и can нужно в времени употребить - could.