为提高朗肯循环的热效率，主要可采用哪几种热力循环方式？
参考答案：
主要采用：给水回热循环、蒸汽中间再热循环、热电联供循环。
_____, he talks a lot about his favorite singers after class.
A．A quiet student as he may be
B．Quiet student as he may be
C．Be a quiet student as he may
D．Quiet as he may be a student
—Mike, you don't seem to be quite today.
—Well, I hardly slept last night. I was preparing for a report.
A．itself
B．ourselves
C．you
D．yourself
