西班牙语课上，老师教我们如何变化动词“hablar”在不同时态下的形式。

In Spanish class, the teacher showed us how to ___conjugate the verb 'hablar' in different tenses.

这两种物质可以结合形成更稳定的化合物。

These two substances can ___conjugate to form a more stable compound.

在研究过程中，科学家们观察到两种细菌偶尔会结合交换基因。

During the experiment, scientists observed that two types of bacteria occasionally ___conjugate to exchange genes.