The seedlings, puny and ankle high when they should be knee high by this time of year, are his second planting.

这些幼苗是他第二次播种的，往年这时候应该到膝盖高了，可现在小得才到脚脖子。

youdao

The grass was knee-high.

草有齐膝高。

《柯林斯英汉双解大词典》

They trekked from shop to shop in search of white knee-high socks.

他们疲惫地奔波于一家又一家商店，寻找高到膝盖的白色长筒袜。

《柯林斯英汉双解大词典》

Mr. MONROE: Nas had a parent who introduced him to blues when he was just knee high to a grasshopper.

NPR: Young People and the Future of the Blues

"King tides and sea surges are floodling the island to a knee high and it is difficult for the salt water to dry up, " says Ursula Rakova, a Carteret islander and campaigner.

CNN: Drowning islands warn of future perils for 'environmental refugees'

When the baby's grandfather was knee high to a cricket, at least according to memories that may be skewed by nostalgia, it was still possible for residents of West Baltimore to remain relatively untouched by the drug life.

ECONOMIST: American slums