解释下列词语。

①忍俊不禁——___________________________________                                    

②盎然——_______________________________________                                        

③柔媚——_______________________________________                                        

④枯瘠——_______________________________________                                        

⑤陆离——_______________________________________                                        

⑥奇崛——_______________________________________  

汽轮机转子以（）为死点沿轴向膨胀或收缩。