1 . 词义猜测，请根据句意指出下列句子中划线单词的词性和汉语意思。
1. Briefly speaking, smoking is one of the major causes of cancer.
2. He majored in history at Stanford.
3. The major part of the town was ruined by the horrible earthquake.
4. English is his major and he has no difficulty communicating with foreigners.