digress
v[I, Ipr]
~ (from sth) turn or wander (from the main topic) in speech or writing 说话或写作时偏离(主题); 离题
Don't digress (from the subject) when lecturing. 讲课时不要岔开(主题).
The currents of air that the walls of the ship direct upwards, as well as in the line of its course, are enough to give the great bird with its immense wings sufficient sustenance and progress.