电，气焊在同一场地作业时，氧气瓶必须采取（）措施，乙炔气瓶要有接地措施。
参考答案：绝缘
--- Walking an hour every day is good for our health.
--- Exactly. However, ________.
A．I love doing it very much.
B．I don’t hate it.
C．Climbing a mountain is also good.
D．I don’t like to do it every day.
A．4：1
B．1：
C．2：1
D．：1
：1