题目

__________ the assignment made his father lose his temper.  A. The boy’s not having done                B. The boy not having done  C. The boy’s having not done                D. The boy having not done 答案：A鸟类的结构与其飞行生活相适应的特征有：（ ）①身体呈流线型，体表被覆羽毛  ②骨骼轻、薄，长骨中空  ③有坚硬的角质喙   ④羽毛颜色鲜艳  ⑤胸骨上有发达的肌肉 ⑥体内有气囊．A．①②③⑤B．①②③④C．②③⑤⑥D．①②⑤⑥