怎么用由？（up to somebody）
my teacher told 由 is up to somebody, but I didn't understand it.Could you help??

Question

怎么用由？ （up to somebody）
my teacher told 由 is up to somebody, but I didn't understand it.Could you help??

Answer

It's up to you.  =  由你 =  it is depend on you.  = 这由你来决定 
It's not up to you.  =  由不了你 = it is not depend on you. = 这不由你来决定

“up to" is only one meaning of 由.

Answer

like if someone ask who is going to have a dinner with me 谁来和我共进晚餐 you answer its up to you.由你决定