I have not seen you for ages.(同义表达）
I have not seen you for（a）（long）（time）
for ages = for a long time很久,很长时间.
I want to choose blue as my bedroom colour.(同义表达）
(I’d) (like) to choose blue as my bedroom colour.
want = would like 想要.
Has your school magazine been published yet?(同义表达）
Has your school magazine (come) (out) yet?
come out = be published 出版,发表.
We have not been told what to do next.(同义表达）
We have not been told what (we) (should) (do) next.
对that提问一般用what,有时也可用用who,具体问题具体分析.
one day = some day）有一天；总有一天；有朝一日.
而in future 表示“今后,往后”,与one day 并不是一对近义词.