下列零部件中,用于平衡发动机在冷态和热态下冷却液体积差异的是()
A、水箱
B、喷水壶
C、副水箱
D、暖风水箱
参考答案:C
You can keep the book for another week, but you ______ lend it to others. [ ]
A. needn't
B. mustn't
C. aren't
D. must
手烧炉出现冒黑烟是由于加煤时燃烧空气量过剩。