Is "一“ in 一线城市 first or second tone?

Question

Quick question: Is "一“ in 一线城市 first or second tone? If it is first tone, is this because it is being used as a number?

Cheers,

Stephen

Answer 1

一 in 一线 has two kinds of tones, and two corresponding meanings:

1. yi1 xian4 (1st tone), means front line / 1st line, such as 一线城市 (first-tier city), 亲临一线, 一线队.

2. yi2 xian4 (2nd tone), means a gleam of / a ray of, such as 一线光明, 一线生机.

Basically, before the word with 4th tone, 一 should be pronounced as the 2nd tone (“一”的音变), such as 一样, 一辈子. But if it is used as ordinal, should use its original tone (the 1st tone), such as 第一名, 第一线. Note in this case 第 could be omitted, but still should keep its original tone (the 1st tone). So if 一 is used as the meaning of 第一 (the 1st), it should always be pronounced as the 1st tone.

Reference:
试析“一”声调的读法
“一”的音变
“一”的变调

Answer 2

一 is First tone here, meaning first class, the best.

Other examples: 一等奖, first prize; 第一, first.

Answer 3

一线城市 is the first tone

Rule number 1: If "一" is for "order", then it is the first tone.

However, 一线天， is the second tone.

Rule number 2: If "一" is for "quantity", then it is the second tone.

Again, in oral Chinese, sometimes rules above are not always right,

e.g. 一辈子， usually ppl use second tone for that, because that can give this word a special emotion (for complaining something.) It is very similar as you are saying this: "I have been working on this sh*t job for my whooooooole life"

Answer 4

See this question about the pronunciation of "一".

To be simple, in 一线城市， 一 is used as an ordinal number, so it is the first tone. Here 一 means first.

In general, 一 is used as a cardinal number, its prononciation varies in function of the context.

Answer 5

I wonder about the idea that yi is read first tone here because it is an "ordinal." According to Chao Yuen Ren's A Grammar of Spoken Chinese (p. 568):

In lexical compounds with stressed yi as 'one', it does not have the tone sandhi, resulting in the 4th or 2nd tone, but always has the 1st tone

Here are some examples of lexical compounds ('words' and 'chengyu') where yi certainly does not mean first. It seems to me that yi is first tone in most of these, but I am not a native speaker.

一刀兩斷
一毛不拔
一股作氣
一目了然

一般
一心
一經
一路

What do you think?