Fricative are often a source of confusion for English learners.

音让很多英语学习者感到困惑。

In today's program, we will explore fricatives.

在今天的节目里，我们要探索音。

These are all fricatives, the sounds are coming out slowly and you hear this friction sound.

这些都是音，声音慢慢地出你听到声。

To be clear, fricatives mean there is a partial obstruction in the air stream.

清楚地说，音指的是气流有一部分被阻滞。

Another type of consonant is a Fricative.

另一种辅音是音。

First, when the thickened layers of the pericardium rub up against each other - it creates a friction rub which can be heard on auscultation.

当增厚的两层心包膜互，可在听诊时闻及心包音。

It usually results in a friction rub, as well as ECG changes like ST elevation and PR depression, followed by T wave flattening and inversion.

通常表现出心包音，以及ST段抬高和PR段压低等心电图改变，继之呈现T波低平和倒置。

So, to make the th sound you already know, I hope that the tongue needs to be outside, and the air has to pass between the tongue and teeth in order to create this friction sound.

所以，要出你已经知道的 th 音，需要舌头在外面，空气必须通过舌头和牙齿之间，才能出音。