digression from something
The lecturer temporarily digressed from her subject to deal with a related theory.讲师暂时将她的主题放在一边，开始讲起了另一相关理论。
Every now and then he would digress from political discussions and write about culture.
Briefly digressing from his theme of confidence and achievement to talk about the financial crisis, he insisted that the UK was well placed to weather the global downturn.

SMART Vocabulary: related words and phrases

Digressing and being indirect or evasive
bury the ledeidiom
candy coat
candy coating
candy-coated
circumlocution
circumlocutory
get on to/onto something
glancingly
gloss over something
go off on a tangentidiom
hedging
implicit
mealy-mouthed
obscure
parry
prevaricate
stray
tangent
unexpressed
unvoiced