【18.Thenumberofregisteredparticipantsinthisyear'smarathonwashalf_____.A.oflastyear's18.Thenumberofregisteredparticipantsinthisyear'smarathonwashalf_____.x0bA.oflastyear'sB.thoseoflastyear'sC.ofthoseoflastyea】

　　18.Thenumberofregisteredparticipantsinthisyear'smarathonwashalf_____.A.oflastyear's

　　18.Thenumberofregisteredparticipantsinthisyear'smarathonwashalf_____.x0bA.oflastyear's

　　B.thoseoflastyear's

　　C.ofthoseoflastyear.

　　D.thatoflastyear's