As we all know, environmental pollution is still serious nowadays. Our group wanted to know how many students knew about each kind of the pollution and we wanted to know how often they sorted（分类） rubbish. So we did a survey among the students in our school. Here are the results of our questionnaire（问卷）.

The results of the questionnaire.

【小题1】The survey is mainly about ______ .

A．scientific research	B．environmental protection
C．everyday habits	D．physical education

【小题2】We can know there are ______ parts in the questionnaire.

A．two

B．three

C．four

D．five

【小题3】______ is known by the fewest students.

A．Air pollution

B．Water pollution

C．Noise pollution

D．Global warming

【小题4】______ have begun to sort rubbish according to the chart（图表）.

A．All of the students

B．Most of the students

C．None of the students

D．Some of the students