4.38 Given $\frac{4}{\sqrt{3}+\sqrt{2}}<x<\frac{4}{\sqrt{5}-\sqrt{3}}$. Then, the number of integers $x$ that satisfy the above inequality is
(A) 4.
(B) 5.
(C) 6.
(D) 7.
(China Junior High School Mathematics League, 1997)
［Solution］After rationalizing the denominator of the given expression, we have

that is
$$
\begin{aligned}
4(\sqrt{3}-\sqrt{2})<x<2(\sqrt{5}-\sqrt{3}), \\
1.27 \cdots<x<7.3 \cdots
\end{aligned}
$$

Therefore, the correct choice is $(\mathrm{C})$.