为防止热水锅炉产生二次水垢，系统回水在进入锅炉之前应流经除污器，再进入锅炉。
参考答案：对
______himself to his lab research, the famous scientist missed ________from the liver cancer.
A．Devoted; being saved
B．Devoting; being saved
C．Devoted; to be saved
D．Devoting; to be saved
化简求值 （-x2+5+4x）-（4-5x+x2） 其中x=-2．
