Definition: 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].

Positive Example 1 -
Input: #1 return secretaries 
#2 return #1 born in state 'Alabama 
#3 return departments managed by #2 
#4 return distinct creation years of  #3
Output: What are the distinct creation years of the departments managed by a secretary born in state 'Alabama'?

Positive Example 2 -
Input: #1 return flights  
#2 return #1 from baltimore 
#3 return #2 to  atlanta 
#4 return #3 that  arrive  before noon  
#5 return #1 from denver 
#6 return #5 to  atlanta 
#7 return #6 that  arrive  before noon  
#8 return #4 ,  #7
Output: I'd like to see flights from baltimore to atlanta that arrive before noon and i'd like to see flights from denver to atlanta that arrive before noon

Negative Example 1 -
Input: #1 return red objects 
#2 return #1 that  are metal 
#3 return blue objects 
#4 return #1 that  are rubber 
#5 return number of  #2 
#6 return number of  #4 
#7 return difference of #5 and #6
Output: How many more metal objects are there than rubber objects?

Negative Example 2 -
Input: #1 return Landmark Theatres 
#2 return Marcus Theatres 
#3 return screens of #1 
#4 return screens of #2 
#5 return number of  #3 
#6 return number of  #4 
#7 return the sum of #5 and #6
Output: How many screens do Landmark Theatres and Marcus Theatres have each?

Now complete the following example -
Input: #1 return flights 
#2 return #1 from boston 
#3 return #2 to  san francisco 
#4 return #1 from san francisco 
#5 return #4 to  boston 
#6 return the  aircraft of #3 
#7 return the  aircraft of #5 
#8 return #6 ,  #7
Output: 



Answer: list types of aircraft that connect boston and san francisco