N-joining

例句：

1. 1. The two molecules are joined together through a strong covalent bond.
   这两个分子通过强共价键结合在一起。
2. 2.The process of joining metals together is called welding.
   将金属结合在一起的过程称为焊接。
3. 3.The scientists are working on a new method to join DNA strands together more efficiently.
   科学家们正在研究一种新的方法，以更高效地连接DNA链。