"在他八岁时"译为英文是什么?(3种)

When he was eight
At the age of eight
in his eighth

When he was eight (years old),
At the age of eight,.../At age eight,...
As he was eight (years old),

如in one's fiftieth 表示在某人五十几岁时

when he is eight
at the age of eight
at age eight

when he was eight
when he was 8 years old
at the age of 8, he....

an eight-year-old boy
when he was eight
at the age of eight

when he is eight ,at his age of eight,the 8th year after he was born