Lesson 17: Save the Tigers1) the number of2) balance 的用法3) danger 的用法I. Learning aims: Master the new words: century, fur, symbol, courage, brave, chain, balance, reason, disappear, kill, cut, decreaseII. Learning important and difficult points:New Wordscentury fursymbol couragebrave chainbalance reason disappear killcut decreaseThink About ItWhere can you usually see a tiger?Do you think tigers need our help? Why or why not?Language Language PointsPoints1. At the beginning of the 20th century, the number of tigers in the wild was around 100 000. 在二十世纪初期，野生老虎的数量大约是十万。 the number of 是固定短语，意为“……的数量”，后接可数名词复数，但中心词是 number ，所以谓语动词要用单数。如： The number of students in our school has grown from 1,000 to more than 1,500. a number of 为量词短语，意为“许多；大量”，相当于 a lot of 或 lots of ，中心词是该短语所修饰的可数名词复数，所以作主语时，谓语动词用复数形式。 如： A number of students like playing computer games. 2. It helps keep the number of other wild animals in balance. 它可以帮助保持其他野生动物的数量平衡。 balance 在句中用作名词，意为“平衡；均衡”，常用短语 be out of balance ，意为“不平衡”； keep in balance 意为“保持平衡”；balance 还作动词，表示“（使）平衡；（使）均衡”。如： You must learn to keep your balance in skating. 在滑冰时你必须要学会保持平衡。 3. In recent years, tigers have been in danger of disappearing. 近年来，老虎已经面临消失的危险。 danger 意为“危险”，通常是不可数名词，表示做某事的危险或发生某情况的危险等，常用短语 be in danger (of) ，意为“在危险中”。如： Is there any danger of fire? 有发生火灾的的危险吗？ExercisesExercises1. ________ ( 长颈鹿 ) are the tallest animals on land.2. What beautiful __________ ( 婚礼 ) clothes they are!3. Uncle Yan visited many ______...
