say in English是用英语说的意思。例如：There are things you can express in Scots that you can't say in English. 有些话可以用苏格兰英语表达，而无法用标准英语表达。speak in English是用英语讲;说英语;用英语说的意思。例如：He made the suggestion that we speak in English in class. 他建议我们在课堂上用英语说话。