诱导阻力在什么时候处于最大（）.
A.前飞时
B.侧飞时
C.上升时
D.悬停时
参考答案：D
下列哪项是哺乳动物特有的特征（ ）
A．心脏四腔
B．体表有毛、胎生、哺乳、有膈
C．盲肠发达
D．体温恒定
The two friends had a quarrel about money, but shortly afterwards they shook hands and _______.
A．broke up
B．made up
C．came up
D．showed up
