R If in space three lines $a, b, c$ are pairwise skew lines, then the number of lines that intersect $a, b, c$ is ( ).
(A) 0
(B) 1
(C) More than 1 but a finite number
(D) Infinitely many
Parse: There exists a unique pair of parallel planes passing through two skew lines, which is the key to solving this problem. Let the parallel planes passing through $b$ and $c$ be $\alpha$ and $\beta$, respectively. Since $a$ is skew to both $b$ and $c$, we can take a point $A$ on $a$ that is not in the planes $\alpha$ and $\beta$ (as shown in the figure), and connect $A$ with any point $N$ on $b$, intersecting $\beta$ at $M'$. As $N$ moves along $b$, $M'$ moves within $\beta$, generating a line $b'$. It is easy to see that $b' \parallel b$, and $b'$ must intersect $c$ at some point $M$. Thus, $AM$ intersects both $b$ and $c$. When $A$ varies, it is evident that a unique line can be found that intersects both $b$ and $c$. Therefore, the correct choice is D.