1. From $1,2, \cdots, 8$, randomly take four different integers, the probability that their sum is odd is $\qquad$ .
\[\begin{array}{l}-1 \cdot \frac{16}{35} . \\ \frac{C_{4}^{1} C_{4}^{3}+C_{4}^{3} C_{4}^{1}}{C_{8}^{4}}=\frac{16+16}{70}=\frac{16}{35} .\end{array}\]