1. away from the point
2. digress
3. off the track
4. beside the point
5. irrelevance
6. stray from the point
7. digress from the subject;
其它相关解释:
<digression> <beside the question> <travel out of the record> <run adrift> <wander from> <vagrancy> <divagate> <come adrift> <wander> <off the point> <wander from the subject> <get off the subject> <beside point> <irrelevancy> <excursion> <irrelvance>
参考资料：dict.cn
最口语的表达是go too far from the subject
out of question.
5知
digress, v.; beat around the bush; off the subject.
off the subject
out of the point
to stray from the point/subject
off the subject
a)off the topic
b)not what the question ask for
