across the line的用法和样例：
- The engine was derailed by a tree lying across the line.
- The engine is derailed by a tree lying across the line.
- He succeeded in propelling the ball across the line.
- The train was delayed because a tree had fallen across the line.
- Motion across the line of sight can be followed by direct observation.
- Motion of a star across the line of si ght causes no change in its spectrum.