There are still some unfounded fears floating around out there about cancer being contagious.社会上还是有一些毫无根据的关于癌症会传染的恐惧。Your report last week was unfair. It was based upon wholly unfounded and totally unjustified allegation...
The choice of players for the team seemed completely arbitrary.看来这个队的队员完全是随意选定的。You can make an arbitrary choice.你可以随便做选择.He makes unpredictable, arbitrary decisions.他做的决定难以预料, 主观武断....