9. After the assembly line malfunction was ______, factory workers were told it would be two hours

before they could resume production

(A)found (B)finds (C)to find (D)find

19.Before they took their morning break, the event organizer _____ attendees about the change of

 speaker for the afternoon session

(A)notify (B)is notifying (C)had notified (D)notifies

22. priscilla and her team members _____ a lot of useful information about  new design trends when

 they attended the trade fair

(A)will gather (B)to gather (C)gather (D)gathered

25. when Mr. McKay returned from his business trip, he noticed that several computer disks

 _____ from his office

(A)had disappeared (B)will be disappearing (C)will disappear (D)are disappearing

27. Analysts believe the public's fear of future economic crises _____ a decrease in consumer

 spending over the year.

(A)were causing (B)has caused (C)causing (D)is caused

답이 되는 이유를 설명해주세요 ㅜㅜ 부탁드릴께요^^