7. Given that $x$ is an acute angle, and $2 \sin ^{2} x-7|\sin x|+3<0$. Then the range of values for $x$ is ( ).
(A) $0^{\circ}<x<30^{\circ}$
(B) $30^{\circ}<x<45^{\circ}$
(C) $30^{\circ}<x<90^{\circ}$
(D) $60^{\circ}<x<90^{\circ}$
7. C

Let $\sin x=t$, then $2|t|^{2}-7|t|+3<0$. Solving this, we get $\frac{1}{2}<|t|<3$. Therefore, $-3<t<-\frac{1}{2}$ or $\frac{1}{2}<t<3$. Since 0 $<\sin x<1$, it follows that $\frac{1}{2}<\sin x<1$. Hence, $30^{\circ}<x<90^{\circ}$.