null adj. 1.無效力的,無束縛力的。 2.無效的,無用的,無益的;無價值的。 3.沒特征[個性]的,沒表情的。 4.〔罕用語〕不存在的,沒有的;零(位)的;空的。 n. 【數(shù)學(xué)】零,零位;空;【無線電】零訊號,微弱訊號。 a null indicator 零示器;零位指示器。 the null method 衡消法。 null and void 【律】無效;失效(This check is null and void. 本支票無效)。 vt. 使無效。
When the redirected stream is closed , a null line is sent to the event handler 當(dāng)關(guān)閉重定向流時,會向事件處理程序發(fā)送一個空行。
By pressiong the 2 buttons , check the side by side lines one by one . if the light is on , it is phase line , otherwise it is the null line , in case there is a break in the line , move until hte light is off . that is the break point 按兩鍵)以鋪好的三芯或四芯電纜或電線,可將另一端全部良好接地,再如圖分別檢測燈亮則通,此法適合樓房裝修布線,將主線接地,邊安裝邊測試。
This thesis not only analysed the serious results of deviation of electricd pressure , which was harm for equipments and personal safety , caused by disconnection of null line , but also proposed effective protecting measure for mulfunction , such as repetition earth protecting measures and so on 摘要分析了零線斷線造成電壓偏移而對設(shè)備和人身安全帶來的嚴(yán)重后果,提出了重復(fù)接地等有效的故障保護措施。