A.  $\left\{\begin{array}{l}x=3+t\\ y=t\\ z=1+t\end{array}\right.$

B. $\left\{\begin{array}{l}x=3-t\\ y=t\\ z=1\end{array}\right.$

C. $\left\{\begin{array}{l}x=3+t\\ y=t\\ z=1\end{array}\right.$

D. $\left\{\begin{array}{l}x=3+t\\ y=-t\\ z=1+t\end{array}\right.$

A.  $∆:\left\{\begin{array}{c}x=1+2t\\ y=-2-4t\\ z=1+3t\end{array}\right.$

B.  $∆:\left\{\begin{array}{c}x=1+2t\\ y=-2-3t\\ z=1+2t\end{array}\right.$

C.  $∆:\left\{\begin{array}{c}x=1+t\\ y=-2-t\\ z=1+3t\end{array}\right.$

D. C

A.  $\left\{\begin{array}{l}x=1+2t\\ y=-2\\ z=3+2t\end{array}\right.$

B.  $\left\{\begin{array}{l}x=-1+t\\ y=2\\ z=-3-t\end{array}\right.$

C.  $\left\{\begin{array}{l}x=1\\ y=-2\\ z=3-2t\end{array}\right.$

D.  $\left\{\begin{array}{l}x=1+t\\ y=-2\\ z=3-t\end{array}\right.$

A.  $\frac{x+1}{-1}=\frac{y+1}{-1}=\frac{z-2}{1}$

B.  $\frac{x-1}{1}=\frac{y}{1}=\frac{z-1}{-1}$

C.  $\frac{x-1}{1}=\frac{y-2}{1}=\frac{z-3}{-1}$

D.  $\frac{x-1}{1}=\frac{y}{-1}=\frac{z-1}{1}$

A. T = 14

B. T = 0

C. T = 21

D. T = 7

A.  $T=14$

B.  $T=0$

C.  $T=21$

D.  $T=7$

A.  $\left\{\begin{array}{l}x=-3\\ y=-5-t\\ z=-3+4t\end{array}\right.$

B.  $\left\{\begin{array}{l}x=-3\\ y=-5+t\\ z=3+4t\end{array}\right.$

C.  $\left\{\begin{array}{l}x=-3\\ y=-5+2t\\ z=-3-t\end{array}\right.$

D.  $\left\{\begin{array}{l}x=-3\\ y=-6-t\\ z=7+4t\end{array}\right.$

A.  $\left\{\begin{array}{l}x=2+t\\ y=2-t\\ z=-1+2t\end{array}\right.$

B.  $\left\{\begin{array}{l}x=1+2t\\ y=-1+2t\\ z=2-t\end{array}\right.$

C.  $\left\{\begin{array}{l}x=1+2t\\ y=-1-t\\ z=1+2t\end{array}\right.$

D.  $\left\{\begin{array}{l}x=2+2t\\ y=2+2t\\ z=-1-t\end{array}\right.$

A. 3x+y-z-3=0.

B. x+2y+3z-6=0.

C. 3x+y-z+3=0.

D. x+2y+3z+6=0.