A:人在憋气时,细胞停止呼吸
B:植物无氧呼吸的产物都是酒精和C02
C:无氧呼吸因为分解糖类的效率低,所以释放的能量少
D:人体剧烈运动时,既进行无氧呼吸,又进行有氧呼吸
It ____ him one hour ____ ____ his homework.
Let him _______ a rest. I think he must be tired after the long walk.