彼は大人になりつつある。の英語

He is approaching manhood.

He's on the threshold of adulthood.

He's barely of age.

He makes a fool of adults.

She has quite grown up.

He is old.

He is getting old.

He is old beyond his years.

He's advanced in years.

He is in his prime―in the prime of his manhood―in the prime of his life.

He is old.

He is old―advanced in age―stricken in years.

He was old.

He grew old.

He is a senior.

He is an elder.

He has an old head on young shoulders.

He's growing old.

He is entering old age.

He is too old.

He's advanced in years.

He grew old.

He looks old for his age.

I'll be an adult soon.

He's gotten old, too.

He is getting old.

He is no longer a boy.

He is old before his time.

His eyes are dim with age.

He is decrepit―senile―infirm with age―old and infirm.