换热器内参与交换的两种流体在传热面的两侧彼此成直角方向流动,此种流动方式为()流。
A、并
B、逆
C、折
D、错
参考答案:D
24=______×______=______×______=______×______=______×______所以,24的因数有______个,其中最大的因数是______,最小的因数是______.
Don't stop ________ you meet with a word you don't understand.[ ]
A. at the time
B. each time
C. by the time
D. sometimes