生活处处有物理,下列关于生活中的物理知识说法错误的是( )
A:用筷子夹取食物时,利用了摩擦力
B:打开醋瓶能闻到酸味说明分子做无规则运动
C:驶员在驾驶车辆时需系上安全带是防止惯性带来的伤害
D:公交车内的破窗锤是通过增大受力面积的方法来减小压强
The boy pretended _______ when the teacher came in.
已知函数f(x)=logax(a>0且a≠1)
(1)当a=3时,求方程f(27x)f(3x)=﹣5的解;
(2)若f(3a﹣1)>f(a),求实数a的取值范围;
(3)当a=12时,设g(x)=f(x)﹣3x+4,求证:对任意λ>0,都存在μ>0,使得g(x)<0对x∈(λμ,+∞)恒成立.
根据短文内容填空。
Jane White is an American girl. She is fifteen. She is a middle school student. Her father is Bill White and her mother is Joan White. Her brother, Bob, is a student, too. He is in a black coat and Jane is in a red sweater.
在土壤侵出液中培养的玉米幼苗长势比蒸馏水中的好,合理的解释是土壤浸出液中含有玉米生长所需要的( )