不稳定平衡
参考答案:
是物体稍偏离平衡位置后,当去掉破坏平衡的力时,也不能再恢复到原来的平衡,这种平衡即为不稳定平衡。
阅读下面短文,按照句子结构的语法性和上下文连贯的要求,在空格处填入一个适当的词或使用括号中词语的正确形式填空。
Mary took off her shoes and ran over the hot sand. She tiptoed into the water, 小题1: (laugh) as a wave washed over her legs. She looked back at her mother, 小题2: was sitting under a big umbrella, holding an apple in one hand and a drink in the 小题3: .
Just then, a big wave came and 小题4: (sweep) Mary's feet, making her fall into the water. She tried to scream, 小题5: swallowed some water instead. She didn't know 小题6: way was up or down. She pushed with her hand against 小题7: sand and came up for air. She screamed desperately and tried hard to swim.
When she 小题8: (final) returned to the shore, Mary ran over to her mother, who was standing up 小题9: a worried look on her face.
But to her mother’s surprise, Mary said, “This is the 小题10: (good) vacation ever, Mum. Come and play with me in the water.”
区别再生障碍性贫血与阵发性睡眠性血红蛋白尿的试验是
A.抗人球蛋白试验
B.酸溶血试验
C.中性粒细胞碱性磷酸酶染色
D.骨髓铁染色
E.过氧化酶染色