Baby boys do not seem to notice the difference in the size of the ball, but girls immediately become excited and begin to make noises that sound like language.

男婴似乎没有注意到球的大小的不同，但女婴立即变得兴奋，并开始发出听起来像是语言的声音。

youdao

Your baby will begin to vocalize long before she can talk.

你的女婴在会说话前很早就要开始咿呀发声了。

《牛津词典》

The babies begin to hatch! The mother penguin returns just in time to see her baby come out of its egg.

企鹅宝宝开始孵化！企鹅妈妈回来的时候正好看到她的宝宝从蛋里出来。

youdao

When baby teeth begin to appear, you can clean them with a wet toothbrush.

VOA: special.2009.03.11

Next year the baby boomers begin to retire on Medicare in earnest, and the year after that on Social Security.

FORBES: A Winning Plan For Social Security Reform

But now employers have started to worry about potential labor shortages once the bulk of baby boomers begin to retire.

FORBES: Work (Part Time) Until You Drop

Third, the economy is performing poorly as baby boomers begin to retire.

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