在有理数中，绝对值最小的数是______．
正数的绝对值是正数；负数的绝对值是正数；0的绝对值是0，
正数大于0，所以绝对值最小的数是0．
故答案为：0．
动词填空。
1. All of the boys must______ (be) here before seven o'clock?
2. Life______ (be) a good teacher.It has taught me how ______ (think)
3.—Who ______ (knock) at the door?
—I ______ (not know).Let me go and see.
4. I'm glad ______ (hear) that you ______ (pass) the exam already.
5.Would you like something ______ (eat)?
电缆竖井和电缆沟应做（）防火隔离，对敷设在隧道和厂房内构架上的电缆要采取（）阻燃措施。
