英语翻译You must be a very good (valuable) worker,for them to al

英语翻译
You must be a very good (valuable) worker,for them to allow you a long leave,and to allow to come back.
这句话里的for是什么意思?因为 的意思?还是接着前面的话在说 good worker for them.这是个什么句子结构啊?for them to
如果for 是因为的意思，后面也应该是个句子，也不该用them啊。如果不是因为的意思 就是 you are a good worker for them........那后面的不定式又表什么呢？有这样的造句形式吗？you are a good worker to allow you a long leave