印染上用的漂白剂有哪些？棉常用的是什么？
参考答案：
次氯酸钠、亚氯酸钠、双氧水；双氧水
—I must apologize for ______ ahead of time.
—That’s all right.
A．not letting you to know
B．not letting you know
C．letting you know not
D．letting not you know
