1.John always does his homework____in order not to make any mistakes.
2.It's ____  to find any excuse when you do something wrong.
3.The factory makes a new type of cars which produces less air____.
4.All the victims were saved and taken to ____ .
5.We all know Mother’s Day is on the ____Sunday of May.            

已知：

回答下列问题：

如图所示，将小砝码置于水平桌面上的薄纸板上，用水平向右的拉力将纸板迅速抽出，砝码的移动很小，几乎观察不到，这就是大家熟悉的惯性演示实验．若砝码和纸板的质量分别为m₁和m₂，各接触面间的动摩擦因数均为μ．重力加速度为g．要使纸板相对砝码运动，求所需拉力的大小的取值范围．