10. The requirements for deciphering codes in modern society are getting higher and higher. In cryptography, the content that can be seen directly is called plaintext, and the content obtained after processing the plaintext in a certain way is called ciphertext. There is a kind of ciphertext that maps the 26 English letters $a, b, \cdots, z$ (regardless of case) to the 26 natural numbers $1,2, \cdots, 26$, as shown in Table 1.
Table 1
\begin{tabular}{|c|c|c|c|c|c|c|c|c|c|c|c|c|}
\hline$a$ & $b$ & $c$ & $d$ & $e$ & $f$ & $g$ & $h$ & $i$ & $j$ & $k$ & $l$ & $m$ \\
\hline 1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 & 9 & 10 & 11 & 12 & 13 \\
\hline$n$ & $o$ & $p$ & $q$ & $r$ & $s$ & $t$ & $u$ & $v$ & $w$ & $x$ & $y$ & $z$ \\
\hline 14 & 15 & 16 & 17 & 18 & 19 & 20 & 21 & 22 & 23 & 24 & 25 & 26 \\
\hline
\end{tabular}

The transformation formula for the sequence number $x$ of the plaintext and the sequence number $y$ of the ciphertext is:
$$
y=\left\{\begin{array}{ll}
\frac{x+1}{2}, & x \text { is odd, and } 1 \leqslant x \leqslant 26 ; \\
\frac{x}{2}+13, & x \text { is even, and } 1 \leqslant x \leqslant 26 .
\end{array}\right.
$$

Using this formula, plaintext can be converted into ciphertext, such as $5 \rightarrow \frac{5+1}{2}=3$, i.e., $e$ becomes $c$; $8 \rightarrow \frac{8}{2}+13=17$, i.e., $h$ becomes $q$.

According to the above formula, if the ciphertext obtained from a certain plaintext is $s h x c$, then the original plaintext is
10. love.

From the known transformation formula, we have
$$
x=\left\{\begin{array}{ll}
2 y-1, & 1 \leqslant y \leqslant 13, y \in \mathbf{N} ; \\
2 y-26, & 14 \leqslant y \leqslant 26, y \in \mathbf{N} .
\end{array}\right.
$$

According to the above transformation formula, we have
$$
\begin{array}{l}
s \rightarrow 19 \rightarrow 2 \times 19-26=12 \rightarrow l, \\
h \rightarrow 8 \rightarrow 2 \times 8-1=15 \rightarrow o, \\
x \rightarrow 24 \rightarrow 2 \times 24-26=22 \rightarrow v, \\
c \rightarrow 3 \rightarrow 2 \times 3-1=5 \rightarrow e .
\end{array}
$$

Therefore, the plaintext of sh $x c$ is love.