1. The bad habit has been engrained in his marrow.
    他的坏毛病已经根深蒂固了。

2. And parents whose child has a fatal disease like cancer might be able to clone the child, creating a twin who could be a bone-marrow (骨髓) donor.
    而那些孩子患有诸如癌症等不治之症的父母也能克隆一个孩子，创造出一个能提供骨髓的双胞胎。