脚手板对接处应设两根横向水平杆，两根横向水平杆的间距不得大于（）mm。
参考答案：300
句型转换
1.We need two teaspoons of salt.(对划线部分提问)
_____ _____ teaspoons of salt _____ we need?
2. Put the pizza on the table.(否定句)
_____ _____ the pizza on the table.
3. There are two pearss on the plate.(一般疑问句)
_____ _____ two pears on the plate?
磷酸一钠及磷酸二钠
ons of salt _____ we need?
the table.(否定句)