Her earliest memory is of singing at the age of four to wounded soldiers.

她最早的记忆是在4岁时为受伤的士兵唱歌。

《柯林斯英汉双解大词典》

youdao

Males in four species started singing significantly earlier in the morning if they lived near streetlights than did their deep forest-dwelling kin.

当它们“活在灯下”，而非像其他亲戚一样“深居林中”时，有四种雄鸟清晨唱歌的时间显著提前了。

youdao

There are four main parts of hip-hop: MCing is singing words or what is called rapping.

VOA: special.2009.10.14

Blackberry's four cheeses--Singing Brook, Violet, Trefoil and Blackberry Blue--are made by cheesemaker Kristian Holbrook and his assistants, who the day I visited included a fresh-faced young woman named Heidi, lacking only a dirndl and a yen to yodel to pass for a Swiss milkmaid.

FORBES: Weekend in the Country

Thanks to the shift from airy falsetto to harmonizing, and the slow but propulsive beat, he sounded as if he were singing from about four feet above the ground.

NEWYORKER: Boyz II Man

Ms. FEIST: (Singing) One, two, three, four tell me that you love me more.

NPR: Hearing a Breakthrough: Feist's 'Reminder'