In a medical malpractice action, plaintiffs appeal, as limited by their brief, from so much of an order of the Supreme Court, Nassau County (Burke, J.), dated May 15, 1981, as denied their motion for an order striking certain interrogatories. Order affirmed insofar as appealed from, with $50 costs and disbursements. Plaintiffs' time to reply to the interrogatories is extended until 20 days after service upon them of a copy of the order to be made hereon, with notice of entry. Plaintiffs failed to object to the interrogatories within the time limit set forth in CPLR 3133 (subd [a]). (See Newark-Wayne Community Hosp. v. Cleaver-Brooks, Inc., 59 A.D.2d 821.) In any event, plaintiffs failed to sustain their burden of proof on the question of whether the information requested required the disclosure of expert testimony, attorney's work product, or material prepared for litigation. (See Koump v Smith, 25 N.Y.2d 287; Stengel v Long Is. Light. Co., 61 A.D.2d 838.) Mollen, P.J., Gulotta, Weinstein and Thompson, JJ., concur.