1．What can I do in reward (回报) for your help?
2．Most parks are open to the public free of charge (收费)．
3．Environment is a popular topic (话题) these days.
4．The scientist observes the moon with the aid (帮助) of a telescope everyday.
5．Before making a decision, consult your parents and friends.
6．Even a casual observer could have noticed that.
7．They had some sort of quarrel years ago, and they haven't spoken to each other ever since.
8．According to the timetable,_there was another train at 6：15.
