下列动物不具有膈的是
A：鱼
B：羊
C：牛
D：猪
— It's dangerous to swim here. Look at the sign.
— Oh, I notice it. Thanks for telling me.
昼夜更替，潮起潮落，地球自转运动产生了许许多多的自然现象。回答下列各题。
