鸟类通过不同的发声方式来吸引配偶。

Birds use various ___vocalisations to attract mates.

我们在森林里录下了鸟类的各种鸣叫声进行研究。

We recorded various bird ___vocalisations in the forest for our research.

在讨论会上，我们鼓励大家自由发表意见。

During the discussion, we encouraged everyone to share their ___thoughts freely.