狗之嗅觉 ( http: / / www.21cnjy.com / ) 犬的嗅觉灵敏度位居各畜之首，眼瞎的狗可以利用 鼻子生活的像正常狗狗。犬灵敏的嗅觉主要表现在两个方面：一是对气味的敏感程度；二是辨别气味的能力。敏感度会因味道的种类而有所差别，约为人类嗅觉的1200倍。狗鼻子大约能辨别200万种不同的气味，而且它还具有高度分析的能力，能够从许多混杂在一起的气味中，嗅出它所寻找的那种气味。犬对气味的感知能力可达分子水平。如当1立方厘米含有9000个丁酸分子时，犬就能嗅到，而在一般情况下每立方厘米的空气中约有268×10.e+16个分子。因此，犬感受丁酸的浓度为3.36×10.e-17二有人将硫酸稀释千万分之一时，犬仍能嗅出，对酸性物质的嗅觉灵敏度要高出人类几万倍。21世纪教育网版权所有 欧洲肺病基金会的调查结果显 示，肺癌是欧洲人的第二大致死癌症。研究发现，经过嗅觉训练的狗能够从100例肺癌病人的呼气采样中闻出71例，对于没有肺癌的采样也能达到372/400的辨别准确率。(
课件网) Unit 5 Whose dog is it 人教版（PEP） 五年级下 PA Let’s learn Let’s sing What’s this It’s a _____. book Let’s learn It’s my book. 同义句 The book is _____. mine Let’s learn Whose book is it It’s _____ book. Chen Jie’s her Let’s learn It’s her book. 同义句 The book is _____. hers Let’s learn Whose book is it It’s _____ book. Mike’s his Let’s learn It’s his book. 同义句 The book is _____. his Let’s learn Whose book is it It’s _____ book. Chen Jie and Mike’s their Let’s learn It’s their book. 同义句 The book is _____. theirs Let’s learn their 同音词 there What’s this It’s a _____. flag Let’s learn It’s our flag. 同义句 The flag is _____. ours Let’s learn What’s this It’s a _____. chair Let’s learn It’s your chair. 同义句 The chair is _____. yours Let’s learn What are these They are _____. chairs Let’s learn They are your chairs. 同义句 The chairs are _____. yours Let’s learn Watch and follow Let’s read 四位同学为一组，朗读课本内容。 It’s her dog. The dog is hers. It’s his dog. The dog is his. It’s their dog. The dog is theirs. It’s my dog. The dog is mine. It’s our dog. The dog is ours. It’s your dog. The dog is yours. 形容词性物主代词（形物代）在 名词 前。 名词性物主代词（名物代）在 句子末。 Let’s read and find （形物代）转化为（名物代） my mine your yours our ours her hers their theirs his his 特殊情况 直接加 ____ s 直接加s 直接加s 直接加s his 还是 ____ his Let’s read and find Whose book is that It’s _____ book. Amy’s It’s _____ book. her Amy’s book her book her book hers Ah! The book is _____. hers Let’s say Whose book is that It’s _____ book. John’s It’s _____ book. his John’s book his book his book his Ah! The book is _____. his Let’s say Whose book is that It’s _____ book. John and Amy’s It’s _____ book. their John and Amy’s book their book their book theirs Ah! The book is _____. theirs Let’s say Look, say and complete 1．he（形容词性物主代词） _____ 2．she（形容词性物主代词） _____ 3．I（形容词性物主代词）_____ 4．you（形容词性物主代词）_____ 5． we（形容词性物主代词）_____ 6．they（形容词性物主代词）_____ his her Time for exercise my ... ...
