下列动物中胸腔纵隔将胸腔分为左右两室，且互不相通，暴露心脏时动物不需做人工呼吸，这种动物是（）
A、兔
B、狗
C、猫
D、猴
参考答案：A
We arrived home at 9:00 in the evening, ________most people had already had supper.[ ]
A. at that time
B. by that time
C. at which time
D. by which time
使用无线灯显调车，（）必须按《技规》中关于灯显信号显示的规定发送显示指令。
