生活在东西伯利亚的亚库特人，居住木屋，身着毛皮服装，运输工具是狗拉雪橇，主要原因是(     )

    Hello，my name is Danny. I am a tall boy. I have a big face and two big eyes. I can read books and write English. I am a good student. I have a happy family. My father and mother are teachers. My father is 35 years old and my mother is 33 years old. My father is tall and thin. He can swim and dive. My mother isn't tall. But she's thin. She can draw nice pictures.

①某外企高管王女士每月定存3000元到银行，2000投入股市，交教育保险1000元

②小张毕业后参加工作，除必要开支外把所有收入全部存入银行

③不惑之年的刘先生，给家人各买了一份商业保险，并根据财力投资了房产和基金等

④张大爷退休后，将自己的积蓄80%投入股市，20%购买某企业债券