A:visit
B:to visit
C:visiting
D:visit
— Can you tell the difference between these two pictures?
— Difference? Oh, no. They look quite .
如图所示,小东用力推放在水平地面上的木箱,木箱静止不动,下列说法正确的是( )
下列说法正确的序号是____
①第一象限角是锐角;
②函数y=log12x2+2x-3的单调增区间为(﹣∞,﹣3);
③函数f(x)=|cosx|是周期为2π的偶函数;
④方程x=tanx,x∈π2,π2只有一个解x=0.