[{"_id":{"$oid":"5fa6cdf065249ffc1282e880"},"ask":["java","what is java","java is"],"answer":"answer"},{"_id":{"$oid":"5fa6cdf065249ffc1282e881"},"ask":["no_java","no_ what is java","no_java is"],"answer":"answer"}]

db.collection.find({"ask":"java is"})