烟气轮机的级数是根据烟气在烟气轮机里的焓降来确定的，一列静叶和一列动叶组成一个最基本的单元，称谓（）。
参考答案：级
It has been laid down that each student must _____ a composition to the teacher once a week.
A．turn in
B．give up
C．put forward
D．bring out
幼儿话剧
