negative sign

例句：

1. 1. The negative signindicates that the number is less than zero.
   负号表示这个数小于零。
2. 2. Theteacher gave a negative sign when he sawthe student's paper.
   老师看到学生的试卷时，做了一个否定的手势。
3. 3. Thenegative sign in the equation means that thevariable is not included in the calculation.
   方程中的负号意味着变量没有被包括在计算中。