Heroes ______ their life ______ becoming the best they can be, whether it is President of the United States, a mother, or a firefighter.

A．prevent…from

B．devote…to

C．prefer…to

D．suffer…from

药物过敏性口炎主要是

A．Ⅰ型变态反应
B．Ⅱ型变态反应
C．Ⅲ型变态反应
D．Ⅳ型变态反应
E．以上都不是