摘要：each of which 在以下為 同位語，非關代。1. An urn contains two balls, each of which is known to be either white or black.2. Q. Many companies set a number of objec... 阅读全文

摘要：have PP是表示"從以前到現在"都直在做的事情Mr. Chen has taught English for 30 years.---表示teach的動作持續了30年,但Mr. Chen has died for 30 years.---就錯了!Mr. Chen 不能死了,隔天再die一次,一直... 阅读全文