历代统治者采取重农政策的根本目的是

     Two men are walking in the park. One is Mr Brown , a worker, the other is Mr Black. Mr Brown is going to a chair. It is by the road. Mr Black is after him. Mr Brown finds Mr Black. Now Mr Black begins to walk faster(更快). Because he wants to get to the chair before Mr Black. Now Mr Black begins to walk faster because he also wants to get to the chair first. Then they both run .Mr Black runs faster than (比) Mr Brown. So he gets to the chair first and sits down on it. Mr Brown runs after Mr Black. When he gets to the chair. He sees Mr Black sitting on it. He is sorry to show a notice(通知)with the words“Wet Paint(油漆未干)”to Mr Black . Now Mr Black knows why Mr Brown is going to the chair.

如图所示，一质量m=0.4kg的小物块，以v₀=2m/s的初速度，在与斜面成某一夹角的拉力F作用下，沿斜面向上做匀加速运动，经t=2s的时间物块由A点运动到B点，A、B之间的距离L=10m．已知斜面倾角θ=30°，物块与斜面之间的动摩擦因数μ= $\frac{\sqrt{3}}{3}$ ．重力加速度g取10m/s²．

化学影响着社会的发展和人们的生活质量。以下说法中，不正确的是（  ）

若函数$y=f\left(x\right)\left(x\in R\right)$满足$f\left(x+1\right)=f\left(x-1\right)$，且$x\in -1,1$时，$f\left(x\right)=1-x^2$，函数$g\left(x\right)=\left\{\begin{array}{c}lgx\left(x>0\right)\\ -\frac{1}{x}(x<0)\end{array}\right.$，则函数$h\left(x\right)=f\left(x\right)-g\left(x\right)$在区间$-5,5$内的零点的个数为(     )