We do that when the sound before is unvoiced.

当其前面音为不发音时，我们会这样做。

And a 'th' at the end of a word is usually unvoiced.

单词末尾“th”音一般也都是清辅音。

So the 'th' at the start of content words is usually unvoiced.

所以实义词前“th”一般都是清辅音。

It's unvoiced because there's no vibration here.

它是无声，因为这里没有振动。

If the first one is unvoiced, the second one will sou nd unvoiced, no matter what you do.

如果第一个辅音是清音，无论怎样，第二个也会是清音。

Now if there is a 'th' in the middle of a word, before a consonant, it's usually unvoiced.

如果在单词、辅音前有一个“th”话，通常都是清辅音。

They have the same tongue and mouth position but one uses air to make the sound, it's unvoiced.

它们舌头和嘴位置是一样，但其一个是不发音。

The first one is voiced, the second one is unvoiced.

第一个是浊音，第二个是清音。

If you look it up in IPA, thank has unvoiced TH, AA as in Bat, NG sound, K.

如果你在 IPA 查找它， thank 有清音 TH，AA 在 Bat ， NG 声音， K。

Now we have an ed ending, the sound before is unvoiced so that ed ending is pronounced as a T.

现在我们有一个 ed 结尾，前声音是清音，所以 ed 结尾发音为 T。

The " s" is unvoiced in the noun form, for those of you who are interested in that sort of thing.

对于那些对这类事情感兴趣人来说， “s” 在名词形式是清音。

S and Z are a pair, they go together because they have the same mouth position, and S is unvoiced, and that's considered strong.

S 和 Z 是一组辅音，它们是一组是因为它们发音位置是一样，S 是清音，而且是一个强音。

The ED ending is a T when the sound before is unvoiced. The K is unvoiced, so the ED ending here is a T.

当前面声音是清音时，ED 结尾是 T。 K 是清音，所以这里结尾 ED 是 T。

Now, if the last sound of the base form of the verb is unvoiced, then that means that there's no vibration or almost no vibration, alright, when you say it.

现在，如果动词基本形式最后一个音是清音，那就意味着没有振动或几乎没有振动， 好吧，当你说它时候。

So, if the sound before the letter T and the word to is unvoiced like here, S is an unvoiced sound S, then the T will probably be a true T.

所以，如果字母 T 前声音和单词像这里一样是清音，S 是清音 S，那么 T 很可能是真正 T。