He was so excited when he received an invitation from his friend to visit Tibet.when 可换 because
问题描述：
He was so excited when he received an invitation from his friend to visit Tibet.when 可换 because
答
根据语境的不同，可以。
用WHEN的时候是，当他收到邀请时，他很兴奋。也可以是BECAUSE，因为他本来就想去*，所以收到了就很兴奋。
答
和so 没关系，这里的so不是“所以”的意思。换成because从语法上讲没有问题，但是句子的逻辑关系变了，以前的句子没有强烈的因果逻辑~~
答
如果把so excited 换成very excited ,就可以用because,否则不行