串联换热器与并联换热器各自有何特点?
参考答案:
串联换热器:增加交换介质间的热交换时间,可缩小介质间换热后的温差。并联换热器:增加交换介质的流量,流体流动阻力小。
在我国,违法犯罪要受到法律的制裁。[ ]
All passengers ______, please fasten your seat belts and remain seated ______ the plane is landing.
A.on board; before
B.abroad; since
C.on the board; after
D.aboard; when