When we talk, sounds usually split into two teams: vowels, where the mouth stays open (like the /ɑː/ in father), and consonants, where we block or squeeze the air (like /t/). A semi-vowel sits awkwardly between those teams. It sounds rather like a vowel — the air is not stopped — but in a word it behaves like a consonant, clinging to the edge of a syllable instead of sitting in the middle as the vowel does.

When we talk我們說話時，sounds usually split into two teams聲音通常分成兩組：vowels母音，where the mouth stays open嘴巴保持張開的（like the /ɑː/ in father像father裡的/ɑː/）, and consonants和子音，where we block or squeeze the air我們會阻擋或擠壓氣流的（like /t/像/t/）。A semi-vowel半元音 sits awkwardly between those teams尷尬地卡在這兩組之間。It它 sounds rather like a vowel聽起來比較像母音 — the air is not stopped氣流沒有被阻斷 — but but in a word但在單字裡 it behaves like a consonant它的行為卻像子音，clinging to the edge of a syllable黏在音節的邊緣 instead of sitting in the middle而不是像母音那樣 as the vowel does坐在中間。

English mainly has two: /w/ as in we and west, and /j/ (the sound, not the letter y) as in yes and you. Some books also treat /r/ this way.

English英文 mainly has two主要有兩個：/w/ /w/ as in we and west像we和west裡的那個, and /j/和/j/ (the sound, not the letter y)（指的是這個音，不是字母y）as in yes and you像yes和you裡的那個。Some books有些書 also treat /r/ this way也把/r/當成這一類。

Teachers sometimes call them glides, because the tongue glides quickly into the next vowel.

Teachers老師 sometimes call them glides有時會把它們叫做glides（滑音）, because因為 the tongue glides quickly into the next vowel舌頭會快速滑向下一個母音。

Though actually the name is a bit of a nickname: it is not half a vowel. It is a vowel-like sound doing a consonant's job.

Though actually不過其實 the name這個名字 is a bit of a nickname算是個小綽號：it is not half a vowel它並不是「半個母音」。It它 is a vowel-like sound是一個聽起來像母音的音 doing a consonant's job卻做著子音的工作。

You will meet the word in pronunciation class, not in the street.

You你 will meet the word會在發音課上遇到這個字 in pronunciation class在發音課上, not in the street而不是在街頭。