Editor'sNote编者说明 1
Lesson 21 1
TextPlantBreeding 1
ConversationASubjectInterestingtoStudentsofAgriculture 8
WordStudyOn(1) 8
Grammar1．简单句 10
2．并列句 11
3．主从复合句 12
4．并列主从复合句 13
5．连词的分类 14
SupplementaryReading(A)IndividualVariationsinSpecies 20
(B)PlantsandTheirUses 23
Lesson 32 28
TextDiseasesofAgriculturalPlants 28
ConversationInoculatingPlants 38
WordStudyOn(2) 39
Grammar1．名词从句 41
2．名词从句作主语 42
3．名词从句作主补语 43
4．名词从句作同位语 43
5．名词从句作宾语 44
SupplemertaryReading(A)TheControlofPlantDiseases 51
(B)TheEffectsofExcessontheHealthof 55
Organisms 55
Lesson 33 58
TextWeatherSatellites 58
ConversationWhyPeopleLiketoTalkAbouttheWeather 63
WordStudy1．Mean 66
2．Send 67
Grammar1．一般过去将来时 68
2．时态的延续 69
3．直接引语和间接引语 70
SupplementaryReading(A)WeatherForecasts 81
(B)RainforGrowingThings 85
Lesson 34 87
TextAnimalsandMan 87
ConversationVisitingtheVeterinaryHospital 96
WordStudyMake 99
SupplementaryReading(A)AnimalHealth 104
(B)Veterinarians 108
ReviewExercises(Lesson31～Lesson34) 111
Lesson 35 115
TextWouldThereBeEnoughFoodforSoManyPeople? 115
ConversationLet'sIncreaseFoodProduction 122
WordStudy1．Present 124
2．Concern 126
2．限制性定语从句 127
Grammar1．定语从句 127
3．非限制性定语从句 132
SupplementaryReading(A)MoreFoodforPeople 142
(B)WaystoEnsureThatWe'11Continue 145
toBeWellFed 145
Lesson 36 149
TextTheEffectofMan'sActivitiesonSoil 155
ConversationAnOralExaminSoil 155
WordStudy1．Certain 161
2．Remain 162
Grammar1．“介词＋whom或which”开始的定语从句 163
2．“名词、代词或数词＋of+whom或which” 165
开始的定语从句 165
3．关系代词和关系副词的省略 166
4．定语从句转换为不定式或分词短语 167
5．强调句型Itis…that 169
SupplementaryReading(A)WhatSoilIs 178
(B)TheSoil 180
Lesson 37 184
TextSportsandGames 184
ConversationATalkAbout“Games”and“Sports” 188
WordStudyGet 191
SupplementaryReadingTheStoryofBallGames 197
ReviewExercises(Lesson35～Lesson37) 205
Lesson 38 211
TextTheBuckwheal 211
ConversationAShortPlay 222
WordStudy1．Opposite 224
2．Still 224
3．Worth,WorthWhile,Worthwhile,Worthy 225
2．时间状语从句 227
Grammar1．状语从句 227
3．地点状语从句 229
4．原因状语从句 229
5．条件状语从句 230
SupplementaryReading(A)TheLovelyAppleTree 238
(B)IntheWoods 242
Lesson 39 246
TextLifeintheUniverse 246
ConversationTelephoning 251
WordStudy1．Cease 254
2．Close 255
Grammar1．目的状语从句 257
2．结果状语从句 260
3．比较状语从句 262
4．让步状语从句 263
5．方式状语从句 265
SupplementaryReading(A)Man'sFirstLandingontheMoon 271
(B)SpaceTravel 274
Lesson 40 278
TextWhatPeopleDon'tKnowAboutAir 278
ConversationIntheDiningHall 284
WordStudy1．Against 287
2．Cause 288
Grammar1．语气 289
2．虚拟语气在条件句中的应用 290
SupplementaryReading(A)Air 299
(B)HowtheEarth'sAtmosphereFormed 300
Lesson 42 303
TextReproduction,CompetitionandEvolution 303
ConnversationOurLibrary 307
WordStudy1．Characteristic 310
2．Prove 310
Grammar1．虚拟语气在某些状语从句中的应用 311
2．虚拟语气在名词从句中的应用 313
3．虚拟语气在Itistime后面的定语从句中的应用 317
4．虚拟语气的其它用法 317
SupplementaryReadingTheLongChainofEvolution 324
Lesson 42 331
TextGeorgeWashingtonCarver 331
ConversationAStrollintheWood 346
WordStudy1．Lack 348
2．Raise 349
SupplementaryReadingBiographicalNotesofFourGreat 354
Biologists 354
ReviewExercises（Lesson38～Lesson42） 360
Appendices附录 368
1．Index索引 368
2．Vocabulary词汇表 382