"Mulți oameni călătoresc singuri."
Traducere:Many people travel by themselves.
A lot of people -o multime de oameni ( poate nu ar trebui trecut ca varianta)
" Many people travel all by themselves." nu este o varianta valida? "All" doar accentueaza ideea de "singur".
By + myself etc.
When we say by + myself, yourself, himself, herself, itself, oneself, ourselves, yourselves, themselves, it means ‘alone’. We sometimes use all for emphasis:
They painted the whole house by themselves! (They did it alone.)
I was all by myself in the house last night but I didn’t mind. (I was alone.)
Did you build that castle all by yourself? (Did you do it alone?)