It is agreed that a person is more likely to suffer from arteriosclerosis ______.
A．as he becomes older
B．if his immune system does not work properly
C．when the cells of his brain and spinal chord decline
D．when the cells in his kidneys decline in number
什么是焊接电弧？焊接电弧有几个机构部分？焊接电弧各区的导电机构的电流组成？
适合在碱性土壤上栽植的是（）
A、栀子花
B、杜鹃
C、油茶
D、柽柳
在干燥而触电危险性较大的环境，安全电压的数值规定为（）。
A、110V
B、36V
C、24V
D、12V
下列植物中不适合在水边种植的是（）
A、池杉
B、水杉
C、落羽杉
D、河柳