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