1. Our class has fifty students. (句意不变, 改写)
    _____ _____ fifty students in our class.
2. Mary does her homework in the evening. (改为一般疑问句)
    _____ Mary _____ her homework in the evening?
3. There is a little water in the glass. (改为特殊疑问句)
    _____ ______ water is there in the glass?
4. Her friend has lunch at school. (改为特殊疑问句)
    ______ ______ her friend have lunch?