问一道英语改错题In order to learn a foreign language well,it is nece

问一道英语改错题
In order to learn a foreign language well,it is necessary to overcome the fear of making mistakes.If the main aim of language use is communication,then mistakes are secondary conditions,which may be dealt with gradually as knowledge of the language (increase).
我把increase改为了increasing,答案是把它改为increases,为什么要这样改呢,