mm

mm — 名詞

1. written abbreviation for millimetre — a unit for measuring short lengths or smal

1.名詞A2
釋義

毫米

長度單位，千分之一公尺

written abbreviation for millimetre — a unit for measuring short lengths or small distances, equal to one thousandth of a metre.

例句

The rainfall measured only 2 mm overnight, so the garden is still dry.

整夜的降雨量只有 2 mm，花園仍然很乾燥。

number + mm measuring natural quantity (rainfall)

Selim cut a 15 mm strip of wood for the shelf he was building.

Selim 裁了一塊 15 mm 寬的木條，用來做他正在組裝的架子。

number + mm as attributive adjective before noun

同義詞
  • millimetre

    the full written form; 'mm' is the standard abbreviation used in measurements

文法句型

number + mm + (long/wide/thick/deep)

number + mm

用法筆記

Used identically in British English (millimetre) and American English (millimeter). The space between the number and 'mm' is optional in informal writing but recommended in formal and technical contexts.

常見錯誤

❌The board is 5 M thick.
✅The board is 5 mm thick.
💡A capital M means 'metres', not 'millimetres'. The abbreviation 'mm' uses two lowercase letters.
❌It measures 0.5 cm' when you mean 5 mm.
✅It measures 5 mm.
💡Note that 0.5 cm equals 5 mm; using mm is clearer for small lengths.

2. mm is short for millimolar — a unit used mainly in chemistry to show how concent

2.名詞C1
釋義

毫莫耳

濃度單位，千分之一莫耳/升

mm is short for millimolar — a unit used mainly in chemistry to show how concentrated a solution is. One millimolar equals one thousandth of a mole of a substance in each litre of liquid.

例句

Quinn prepared a 5 mm solution of sodium chloride for the experiment.

Quinn 為實驗配製了 5 mm 的氯化鈉溶液。

number + mm + solution + of + substance (concentration pattern)

The lab report stated that the calcium level was 2.5 mm.

實驗報告指出鈣離子濃度為 2.5 mm。

number + mm used alone, referring to concentration

文法句型

number + mm + of + substance

number + mm

用法筆記

Almost exclusively used in written lab work and scientific publications. In spoken chemistry, the full word 'millimolar' is preferred.

常見錯誤

❌The solution was 5 M' (when you mean 5 mm).
✅The solution was 5 mm (millimolar).
💡A capital M means 'molar' (moles per litre), while a lowercase 'mm' means 'millimolar' (one thousandth of that).