阅读下面材料，在空白处填入适当的内容（1个单词）或括号内单词的正确形式。

    Some time ago, a light passenger plane flew ____ course(航线) and thus crashed in the mountains and the pilot ____(kill). The only passengers, a young woman and her two baby daughters, were unhurt. It was the middle of winter. Snow ____(lie) thick on the ground. The woman knew that the nearest village was kilometers away and she was not strong enough ____(carry) her baby daughters there. When it grew dark, she turned the suit-case into a bed, where the children,____ (cover) with all the clothes she could find, could be protected from the wind. During the night, it got ____(terrible) cold. The woman kept as near as she could to the children and even tried to get into the case herself, but it was too small. Early next morning, she heard planes ____(fly) overhead and wondered how she could send a signal. Then she had an idea. She wrote the letters SOS in the snow. Luckily, a pilot saw ____signal and sent a message by radio to the nearest town. It was not long ____a helicopter arrived on the scene to save the ____ (survive) of the plane crash.