分类：教育/科学-外语学习-英语考试
问题：areto怎么这么用ThosewhowanttogotoTibe 
The who want to go to Tibet are to sign their names here.are to 翻译为必须，须  be to 是一个词组吗？   还是接的动词不定式
回答：be to 等于一个动词不定时短语。
例如：
You are to understand the meaning of "Those who want to go to Tibet are to sign their names here." I am to explain it.