Select the abbreviation that tells how the italicized noun clause is used. S-subject, DO-direct object, SC-subject complement, OP-object of preposition

Have you discovered where you left your books?

S
OP
SC
DO

  i think you forgot to put the options but if your reffering to this question then your answer will be "b"  a. add "to" to the base form to create an adjective.b. when the subject of a sentence is singular, add "–s" to the base form.c. add "–ed" to irregular base forms to form the past participle.d. do not use a base form with plural subjects