In this task, you will be given a passage to read. A fill in the blank question will be given to you.  Your answer should fit the blank appropriately.

Example Input:  In addition to the reactions originally reported by Johnson , Corey , and Chaykovsky , sulfur ylides have been used for a number of related homologation reactions that tend to be grouped under the same name . With epoxides and aziridines the reaction serves as a ring @-@ expansion to produce the corresponding oxetane or azetidine . The long reaction times required for these reactions prevent them from occurring as significant side reactions when synthesizing epoxides and aziridines . Several cycloadditions wherein the ylide serves as a nucleophilic carbenoid equivalent  have been reported . Living polymerizations using trialkylboranes as the catalyst and ( dimethyloxosulfaniumyl ) methanide as the monomer have been reported for the synthesis of various complex polymers . fill in the blank  :  __________________ addition to the reactions orig__________________ally reported by Johnson , Corey , and Chaykovsky , sulfur ylides have been used for a number of related homologation reactions that tend to be grouped under the same name . 
Example Output:  In 

Example Input: As with previous Valkyira Chronicles games , Valkyria Chronicles III is a tactical role @-@ playing game where players take control of a military unit and take part in missions against enemy forces . Stories are told through comic book @-@ like panels with animated character portraits ,with characters speaking partially through voiced speech bubbles and partially through unvoiced text . The player progresses through a series of linear missions , gradually unlocked as maps that can be freely scanned through and replayed as they are unlocked . The route to each story location on the map varies depending on an individual player 's approach : when one option is selected the other is sealed off to the player . Outside missions , the player characters rest in a camp , where units can be customized and character growth occurs . Alongside the main story missions are character @-@ specific sub missions relating to different squad members . After the game 's completion , additional episodes are unlocked , some of them having a higher difficulty than those found in the rest of the game . There are also love simulation elements related to the game 's two main heroines , although they take a very minor role .fill in the blank  :  As with previous Valkyira Chronicles games , Valkyria Chronicles III is a tactical role @-@ playing game where players take control of a military unit and take part in missions against __________________ forces . 
Example Output:  enemy 

Example Input:   The planning system is critical to the viability and operation of GA aerodromes . With many cities lacking scheduled air transport services between them , and with GA access to commercial airports becoming increasingly difficult and expensive , a viable network of aerodromes supporting GA air transport operations is regarded as an important national issue . However , there is no unified national planning policy specific to GA aerodromes , and planning decisions relating to these are based on local issues that are not required to consider the national impact . Because aircraft are excluded from noise control legislation , the only recourse for people affected by aircraft noise is through the planning process , and this issue is the principal factor on which the majority of planning decisions relating to GA land use are made . GA is a specialist subject often unfamiliar to Local Planning Authorities , and most planning decisions relating to GA either refuse permission , or grant it with restrictive conditions . Little Gransden is just one example of a GA airfield required to comply with planning restrictions on the number of movements permitted , thereby inhibiting further development . Such restrictions , if poorly conceived , can make GA operations unviable or even unsafe . fill in the blank  : The planning system is __________________ to the viability and operation of GA aerodromes . 
Example Output:
 critical 

