将等物质的量的Na₂O和Na₂O₂分别投入到足量且等质量的水中，得到溶质质量分数分别为a％和b％的两种溶液，则a和b的关系是 （    ）

After that, he knew he could _______ any emergency by doing what he could to the best of his ability.

I don't know when I s____last night．

已知函数$f\left(x\right)$满足$f(x+1)=\frac{1}{f\left(x\right)}$，且$f\left(x\right)$是偶函数，当$x\in 0,1$时，$f\left(x\right)=x^2$，若在区间$-1,3$内，函数$g\left(x\right)=f\left(x\right)-kx-k$有4个零点，则实数k的取值范围是（   ）

晚清一位思想家说：“二千年来之政，秦政也，皆大盗也；二千年来之学，荀学也，皆乡愿也。惟大盗利用乡愿；惟乡愿媚大盗。”号召人们冲破君主和伦常的网罗，同封建束缚彻底决裂。这位思想家是