Or , if the electrician can begin wiring display cases after half the cases are installed , the " install and position case lights " task can start when the " install wood and glass cases " task is 50 percent complete , regardless of the duration of the predecessor task . 或者,如果電器工程師可以在燈具裝好一半的時候開始鋪設(shè)線路,則任務(wù)“燈具通電”在任務(wù)“安裝燈具”完成了50 %的時候開始,而不必考慮前置任務(wù)工期的長短。