Поставить глаголы в правильную форму
In most professional play and some amateur competition, there is an officiating head judge or chair umpire (usually referred to as the umpire), who (1) ………. (sit) in a raised chair to one side of the court. The umpire has absolute authority to make factual determinations. The umpire may be assisted by line judges, who determine whether the ball (2) ………. (land) within the required part of the court and who also (3) ………. (call) foot faults. There also may be a net judge who determines whether the ball has touched the net during service. The umpire has the right to overrule a line judge or a net judge if the umpire is sure that a clear mistake (4) ………. (make). In some tournaments, line judges who would be calling the serve, (5) ………. (assist) by electronic sensors that beeped to indicate the serve was out. This system was called "Cyclops". Cyclops (6) ………. since largely ………. (replace) by the Hawk-Eye system. In professional tournaments using this system, players (7) ………. (allow) three unsuccessful appeals per set, plus one additional appeal in the tie-break to challenge close line calls by means of an electronic review. The US Open, Miami Masters, US Open Series, and World Team Tennis (8) ………. (start) using this challenge system in 2006 and the Australian 24 Open and Wimbledon introduced the system in 2007. In clay-court matches, such as at the French Open, a call may be questioned by reference to the mark left by the ball's impact on the court surface. The referee, who (9) ………. usually ………. (locate) off the court, is the final authority about tennis rules. When called to the court by a player or team captain, the referee may overrule the umpire's decision if the tennis rules (10) ………. (violate) (question of law) but may not change the umpire's decision on a question of fact. If, however, the referee is on the court during play, the referee may overrule the umpire's decision.