$S_1={\int }_1^2{x}^{2}dx,S_2={\int }_1^2\frac{1}{x}dx,S_3={\int }_1^2{e}^{x}dx$若 ，则$S_1,S_2,S_3$的大小关系为

$S_1<S_2<S_3$ $S_2<S_1<S_3$ $S_2<S_3<S_1$ $S_3<S_2<S_1$