May I ask you a question, teacher? What's the depth of Lake Lugano?
I guess, not.
I'm not certain what your question is. " would probably be more common. " to make it clear that it is the maximum that you want.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
I'm not certain what your question is. "What's the depth of Lake Lugano?" is valid English, if that is what you are asking, though "How deep is Lake Lugano?" would probably be more common. You can also ask "What's the maximum depth of Lake Lugano?" to make it clear that it is the maximum that you want.
If you literally want to know the depth of Lake Lugano, look at