动植物拾趣PDF电子书下载

Contents 1

1．Can animals understand each other？ 1

2．Do animals laugh or cry？ 3

23．Why do salmon go upstream to spawn？ 5

3．Can animals taste ？ 5

4．What is the fastest four-legged animal？ 7

5．What animals live the longest？ 9

6．Why do animals hibernate？ 11

7．When was the cow domesticated？ 13

8．Why does a cow chew its cud？ 15

9．Why do cows give milk？ 17

10．How are seeing-eye dogs trained？ 19

11．When were cats domesticated？ 21

12．From what animal is the horse descended？ 23

13．Why is the lion called“king of beasts”？ 25

14．Are all apes equally intelligent？ 27

15．Why do birds have feathers？ 29

16．Why do birds sing？ 31

17．What is the largest flying bird？ 33

18．Why do geese fly in formation？ 35

19．What keeps a duck afloat？ 37

20．Why is the owl considered wise？ 39

21．Can a hummingbird stand still in mid-air？ 41

22．How do flying fish fly？ 43

24．How can a snake move without legs？ 47

25．Which snakes are poisonous？ 49

26．Do rattlesnakes rattle before they strike ？ 51

27．How does the rattlesnake rattle？ 53

28．What is the largest snake in the world？ 55

29．Do sharks eat people？ 57

30．Why does a whale spout？ 59

31．What happens to frogs in the winter？ 61

32．What is the difference between frogs and toads ？ 63

33．How do snails get their shells ？ 65

34．What is a shell？ 67

35．What is a sponge？ 69

36．How do insects breathe ？ 71

37．How many kinds offlies are there ？ 73

38．What is the fruit fly ？ 75

39．What is the purpose ofa firefly’s light ？ 77

40．How many bees in a beehive ？ 79

41．How do bees make honey ？ 81

42．How do bees communicate ？ 84

43．Do bees die after they sting ？ 86

44．How does a caterpillar become a butterfly ？ 88

45．How do silkworms makesilk ？ 90

46．Why aren’t spiders caught in their own webs ？ 92

47．What is the spider’s web made of？ 93

48．What do wasps use to build nests ？ 96

49．What do ants eat？ 98

50．How do earthworms eat？ 100

51．Why do moths eat wool？ 103

52．Why do mosquito bites itch？ 105

53．Why do crickets sing？ 107

54．How did dinosaurs come to be？ 109

55．Was there ever such a bird as the dodo？ 111

56．Why do elephants have trunks？ 113

57．What is a vampire bat？ 115

58．How do bats see？ 117

59．What is a lemming？ 119

60．What is a platypus？ 121

61．How does a chameleon change its colors？ 123

62．Do crocodiles attack human beings？ 125

63．Why does a bull charge at a red cloth？ 127

64．Does an ostrich hide its head in the sand？ 129

65．What makes a skunk smell？ 131

66．Do raccoons wash their food ？ 133

67．Why do jellyfish sting？ 135

68．Can groundhogs predict weather？ 137

69．Why does the kangaroo have a pouch？ 139

70．Why does the giraffe have a long neck？ 141

71．What is protoplasm？ 143

72．What is cellulose？ 146

73．What is chlorophyll？ 148

74．What is a seed？ 150

75．How do trees grow ？ 152

76．What gives flowers their scent and color ？ 154

77．Why do leaves have different colors in the fall？ 157

78．How can cacti live without water？ 159

79．What is moss？ 161

80．How do algae grow 163

81．What is mildew？ 165

82．What are fungi？ 167

83．How can you tell poisonous mushrooms？ 169

84．What is a germ？ 171

85．Where do bacteria come from？ 173

Glossary 175