I _____(tell) him the thing as soon as he_____(return) home

I _____(tell) him the thing as soon as he_____(return) home
I _____(tell) him the thing as soon as he_____(return) home

I _____(tell) him the thing as soon as he_____(return) home
will tell returns

will tell
as soon as 与一般现在是连用，所以用returns

一楼正确，as soon as 是条件句，条件句前半部分用将来时，后半部分用一般现在时

will tell returns