实际空气量与理论空气量的比值称为（）系数。
参考答案：过剩空气
It is often said that home is _______ the heart is and now part of my heart is with my new classmates.
A．what
B．how
C．where
D．when
最常见的直肠息肉，多为单发、有蒂，直径一般在1cm以下，很少癌变
A．增生性息肉B．管状腺瘤C．绒毛状腺瘤D．幼年性息肉E．炎性息肉
