Hola Mary
Here "debe ser" means "must be" but not as an obligation; here the verb deber is used to express an "assumption", as in saying "It must be [probably is] such a nice show!"
Here is a Kwiziq lesson that will help you with this specific use of deber (or also deber de)
I hope it helps.
Saludos
Inma
"deber ser" = "debe ser", esto se usa en expresiones imperativas, se usa para expresar una obligación, tales como "Tú debes de comer toda tu comida", "Yo deberia decir la verdad", "Ellos deben obedecer a sus padres".
Hola Carolyn
Yes! There's a typo there!
It should say "...debe ser".
We'll correct it as soon as possible.
Muchas gracias
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