1. l：luminance; 发光度

2. l：left; 左面

3. l：labelling; 标记

4. l：left on base; 残垒

1. 英语字母表的第12个字母
L is the twelfth letter of the English alphabet.

2. （英国的）“驾驶学员”标志（白底红字的大 L 标记，贴于车上）
L is the symbol for 'learner driver' in Britain. A large red 'L' on a white background is attached to cars in which people are learning to drive.

3. （用于首字母为l的一些单词的缩写，如litre和lire）
L or l is used as an abbreviation for words beginning with l, such as 'litre' and 'lire'.