Are comma needed?

[kohyoongliat]

The cat(,) which was dashing across the road(,) was run over by a car.

Is it necessary to insert comma as shown above?

Many thanks.

[Joany]

A comma is needed, but maybe the sentence should have been phrased another way?
The cat was run over by a car when it dashed/ran across the road.
When the cat dashed/ran across the road it was ran over by a car.
Hope this helps.
Joany

[kohyoongliat]

A comma is needed, but maybe the sentence should have been phrased another way?
The cat was run over by a car when it dashed/ran across the road.
When the cat dashed/ran across the road it was ran over by a car.
Hope this helps.
Joany

1. Shouldn't it be 'was run'?

2. Does 'When the cat dashed across the road ...' suggest that it had successfully crossed the road? If so, it is safe.

Many thanks.