The following is a true story. It happened in a small village in Australia, where some dangerous animals live in the forest. Lisa, a 33-year-old mother, went to cook lunch in the kitchen, her 3-year-old son, Barney, playing by himself in the garden. Suddenly, a loud cry of Barney came into the mother's ears. Lisa rushed into the garden in a hurry and found a big snake entwining the little boy with its terrible body and trying to eat the boy. It was a boa . Lisa was _ and quite angry. She decided to save her son from the boa's mouth. It was great mother's love that made Lisa forget what she was facing. She took up a hoe from the ground and beat the boa as hard as she could. One...two...with the hoe, Lisa beat the boa time and time again, but useless. The little boy's voice and breath were getting weaker and weaker. Lisa's heart was broken and she got nearly mad. Suddenly Lisa put away the hoe and threw herself to the boa, opened her mouth and bit into the boa's back. The boa was so badly hurt that it let go of Barney and moved into the forest hurriedly. It had never known how a woman had such terrible sharp teeth. Soon the boa was found dead in the forest. It was great mother's love that saved the little boy. In this passage the writer mainly wants to tell us   _  .
a boa is a dangerous animal how great mother's love is how sharp the woman's teeth are the boy is too young to fight against the boa