1. Their sleeping- bags were warm and comfortable, so they all slept soundly.
    他们的睡袋又暖和又舒服，所以都睡得很香。

2. Their sleeping- bags were warm and comfortable, so they all slept soundly.
    他们的睡袋又暖和又舒服，所以都睡得很香。

3. Their sleeping bags were warm and comfortable, so they all slept soundly.
    睡袋既暖和又舒服，所以，他们都睡得很香。