一篇英语短文改错,
Once a place crashed and it's pilot was killed.The only passengers,a young man and her babies daughters,were unhurt.When it grew dark,she turned a suit-case into a bad and put the children inside it,cover them with all the clothes.During the night,it got terribly coldly.The woman even tried get into the case herself,but it was very small.Early the next morning,she heard planes passing from overhead and wondered how to send signals.She stamped out the letters "SOS" in the snow.Fortunately,they was rescued by a pilot.