1. Given a real geometric sequence $\left\{a_{n}\right\}$ with common ratio $q(q \neq 1)$, set $b_{1}=a_{1}+a_{2}+a_{3}, b_{2}=a_{4}+a_{5}+a_{6}, \cdots, b_{n}=$ $a_{3 n-2}+a_{3 n-1}+a_{3 n}, \cdots$, then the sequence $\left\{b_{n}\right\}$
A. is an arithmetic sequence
B. is a geometric sequence with common ratio $q$
C. is a geometric sequence with common ratio $q^{3}$
D. is both an arithmetic sequence and a geometric sequence
1. C Since $\frac{b_{n+1}}{b_{n}}=\frac{a_{3 n+1}+a_{3 n+2}+a_{3 n+3}}{a_{3 n-2}+a_{3 n-1}+a_{3 n}}=q^{3} \cdot \frac{a_{3 n-2}+a_{3 n-1}+a_{3 n}}{a_{3 n-2}+a_{3 n-1}+a_{3 n}}=q^{3}$, therefore $\left\{b_{n}\right\}$ is a geometric sequence with a common ratio of $q^{3}$.