雅思听力 Part 4 · Canadian Maple Syrup

31 The production of sap needs a climate where night and day temperatures are very .

32 Folk stories claim that maple syrup was first used to cook .

33 Sap collection in spring developed into a First Nations .

34 Syrup was concentrated by using hot stones to produce ,

35 and by leaving it outside at night and removing the layer of on top.

36 European settlers put the syrup in various types of .

37 Its use for making sugar declined after 1880, when the on Caribbean sugar was removed.

38 Harvests may be affected by storms and destructive .

39 Maple syrup is expensive and faces considerable .

40 It is quite compared with other sweeteners.