1. (1990 National College Entrance Examination) The vector corresponding to the complex number $1+i$ is rotated clockwise by $\frac{2 \pi}{3}$. The complex number corresponding to the resulting vector is ( ).
A. $\frac{1-\sqrt{3}}{2}+\frac{-1+\sqrt{3}}{2} \mathrm{i}$
B. $\frac{-1+\sqrt{3}}{2}+\frac{-1-\sqrt{3}}{2} \mathrm{i}$
C. $\frac{-1+\sqrt{3}}{2}+\frac{1-\sqrt{3}}{2} \mathrm{i}$
D. $\frac{1-\sqrt{3}}{2}+\frac{-1-\sqrt{3}}{2} \mathrm{i}$
1. B. Reason: $\arg (1+i)=\frac{\pi}{4}$,

Let $z_{1}=1+\mathrm{i}$.
After rotating the vector $\overrightarrow{O Z}_{1}$ clockwise by $\frac{2 \pi}{3}$, the resulting vector is $\overrightarrow{O Z}_{2}$, as shown in the figure, $\overline{O Z}_{2}$ is in the fourth quadrant, and $\tan \left(\arg z_{2}\right)<-1$, hence the answer is B.