How far back in time could we go in the UK before we would start to be unable to understand the English of the day?
How far back would we have to go for a current English native speaker to have trouble understanding an English speaker from the past?
How long would it take to learn how to speak English like a native speaker? How long does it take to learn English to be like a native English speaker? Is it hard for a native English speaker to study grammar? How can I be an English native speaker? How do I find English native speaker? How can I be a native English speaker? Is it impossible or difficult for native English speakers (Anglophones) to learn foreign languages? How can I understand English native speakers' speaking? How long does it take native English speaker to learn dutch fluently? Does having a native English accent hinder the learning of foreign languages? What is most difficult thing about learning English for non-native speakers? Are native English speakers used to learning other languages? How can I find native English speakers? How do native speakers learn English? What makes you think a foreigner  speaks English like a native speaker? How do I speak English as native speaker? What do non-native speakers find most difficult about learning English? How can I find an English native speaker to practice English online? How do i speak english like a native speaker? How do native English speakers acquire vocabulary? How can I speak English well as native speakers ? How do I talk like a native English speaker? Is it appropriate for a non-native speaker to teach English? What kind of impression do Americans get when a foreigner's English is not native level but speaks in American accent? Why does it seem non-native English speakers say "actually" a lot more than native speakers? How is the best way to find a native speaker who intend to learn English language online with me? How can someone that speaks fluent English with a strong foreign accent acquire a more native accent? How do native English speakers increase vocabulary? As a English learner, should I stick to an American or a British accent? How do native English speakers pronounce a word they have never seen before?