A:细胞呼吸的中间产物丙酮酸可以通过线粒体双层膜
B:是否产生二氧化碳是有氧呼吸与无氧呼吸的主要区别
C:高等植物进行有氧呼吸,低等植物进行无氧呼吸
D:种子库中贮藏的风干种子不进行细胞呼吸
—Alice, why didn’t you come yesterday?
—I ______, but I had an unexpected visitor.
_______he had failed many times, he didn't give up and succeeded in the end.