Kinds of Sentences:
according to construction _____________ according to expression
‘according to construction’ = depending on the number of subject parts and predicate parts used in the sentence
‘according to expression’ = depending on whether some information given; a question asked; an order given, or a surprise , wonderment or fright expressed in the sentence.
Any given sentence must belong to any one of the kinds according to the construction, and any one of the kinds according to the expression.
Are all the boys singing and (are) all the girls dancing?
This sentence is:
a Compound Sentence according to construction
an Interrogative Sentence according to expression.