A:shouldn't have enjoyed
B:needn't have enjoyed
C:wouldn't have enjoyed
D:couldn't have enjoyed
能引发肺炎的肺炎双球菌与酵母菌相比,不具有的结构是( )
①体积 ②容积 ③表面积
①C→CO→CO2②Cu→CuO→CuSO4 ③CaCO3→CaO→Ca(OH)2④Na2CO3→NaCl→NaNO3.