null adj. 1.无效力的,无束缚力的。 2.无效的,无用的,无益的;无价值的。 3.没特征[个性]的,没表情的。 4.〔罕用语〕不存在的,没有的;零(位)的;空的。 n. 【数学】零,零位;空;【无线电】零讯号,微弱讯号。 a null indicator 零示器;零位指示器。 the null method 衡消法。 null and void 【律】无效;失效(This check is null and void. 本支票无效)。 vt. 使无效。
When the redirected stream is closed , a null line is sent to the event handler 当关闭重定向流时,会向事件处理程序发送一个空行。
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 按两键)以铺好的三芯或四芯电缆或电线,可将另一端全部良好接地,再如图分别检测灯亮则通,此法适合楼房装修布线,将主线接地,边安装边测试。
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 摘要分析了零线断线造成电压偏移而对设备和人身安全带来的严重后果,提出了重复接地等有效的故障保护措施。