9.用数字2,3组成四位数,则数字2,3至少都出现一次的四位数的概率是( )
| A. | $\frac{1}{8}$ | B. | $\frac{7}{8}$ | C. | $\frac{3}{4}$ | D. | $\frac{1}{3}$ |
8.化简$\overrightarrow{AB}$+$\overrightarrow{BC}$+$\overrightarrow{CA}$等于( )
| A. | $\overrightarrow{AD}$ | B. | $\overrightarrow 0$ | C. | $\overrightarrow{BC}$ | D. | $\overrightarrow{DA}$ |
6.已知sinα=-$\frac{3}{5}$,且α是第三象限角,则cosα=( )
0 233434 233442 233448 233452 233458 233460 233464 233470 233472 233478 233484 233488 233490 233494 233500 233502 233508 233512 233514 233518 233520 233524 233526 233528 233529 233530 233532 233533 233534 233536 233538 233542 233544 233548 233550 233554 233560 233562 233568 233572 233574 233578 233584 233590 233592 233598 233602 233604 233610 233614 233620 233628 266669
| A. | -$\frac{2}{5}$ | B. | -$\frac{4}{5}$ | C. | $\frac{3}{5}$ | D. | $\frac{4}{5}$ |