Breakdown of Las sábanas están secas, las estoy doblando.
estar
to be (location/state)
seco
dry
doblar
to fold
las
them (feminine direct object)
Questions & Answers about Las sábanas están secas, las estoy doblando.
Could I attach the pronoun las to the end of the verb instead?
Yes! Because this sentence uses a gerund (the "-ing" form, doblando), you have two options for the pronoun las ("them"). You can put it before the conjugated verb (las estoy doblando) or attach it directly to the end of the gerund (estoy doblándolas). Both are perfectly natural, but notice that attaching it requires adding an accent mark to keep the pronunciation the same.
Why does the word las appear twice in this sentence?
They are actually two different types of words that happen to look identical. The first las in Las sábanas is the plural feminine article meaning "the". The second las in las estoy doblando is a direct object pronoun meaning "them", which refers back to the sheets.
Why do we use están (from estar) rather than son (from ser) for "are dry"?
What verb does doblando come from?