In this task, you will be given a set of steps that are required to answer a specific question. Your job is to generate that question. Each given step refers to either an entity (known or unknown), a propery of an entity or a query operation (count, group, union, etc.) Knowing those operations and how they appear in the input may help you generate more accurate questions.
 Select: A select step is used to return a set of objects. There are no references to previous steps in a select step. template: Return [attributes]
 Filter: A filter step is used to return results from a previous step to which a certain condition applies. template: Return [#step] [condition]
 Project: A project step should return certain attributes of the results of a previous step. template: Return [attributes] of [#step]
 Aggregate: An aggregate step returns an aggregator function applied on a step's result. template: Return the [aggregator] of [#step].
 Group: A group step is an aggregator applied on attributes. template: Return the [aggregator] of [#step] for each [attribute]
 Superlative: A superlative step is used to return the result with a highest/lowest attribute among other results. template: Return [#step1] [where] [#step2] [is] [highest / lowest]
 Comparative: A comparative step is used when we need to compare an attribute with a number to filter results. template: Return [#step1] [where] [#step2] [comparator] [number] 
 Union: A union step is used to return results of two steps together. template: Return [#step1] [or / ,] [#step2]
 Intersection: An intersection step returns the result that two steps have in common. template: Return [attribute] of both [#step1] and [#step2]
 Discard: A discard step returns result of a step and excludes result of another step from it. template: Return [#step1] besides [#step2]
 Sort: A sort returns result of another step in a specific order. template: Return [#step1] [ordered / sorted by] [#step2]
 Is true: An is true step checks a condition on another result and returns a true or false. template: Return [is / if] [condition]
 Arithmetic: An arithmatic step operates an arithmatic operation on one or more steps. template: Return the [arithmetic op.] of [#step1] [and] [#step2].

#1 return countries 
#2 return airports of #1 
#3 return elevation of #2 
#4 return average of #3 for each #1
Find the average elevation of all airports for each country.

#1 return puppies 
#2 return #1 that are german shepherd 
#3 return number of  #1 
#4 return number of  #2 
#5 return if  #3 is equal to  #4 
#6 return images 
#7 return number of  #1 for each  #6 
#8 return #6 where  #7 is at least two 
#9 return number of  #6 
#10 return number of  #8 
#11 return if  #9 is equal to  #10 
#12 return if  both  #5 and #11 are true
If only german shepherd puppies are shown, and each image includes at least two puppies.

#1 return flights 
#2 return #1 from philadelphia 
#3 return #2 to  dallas 
#4 return #3 arriving before 4pm 
#5 return #4 on saturday

flight from philadelphia to dallas arriving before 4pm on saturday