语法上有错，它不是个句子，because连接的原因从句中缺少主语，并且没有主句。举两个例子你就明白了：
He was writting to you because he missed you. （因为他想你，所以他给你写信。）
I am here because I miss you. （因为我想你，所以我来这里了。）
because of 也是“因为”的意思，不过应该是because of sth/doing sth. 譬如：He was writting to you because of missing you so much.
温馨提示：答案为网友推荐，仅供参考