He makes unpredictable, arbitrary decisions.

　　他做的決定難以預料，主觀武斷。

　　Arbitrary arrests and detention without trial were common.

　　隨意逮捕和拘留屢見不鮮。

　　The court became notorious for its arbitrary methods and severe punishments.

　　該法庭因其獨斷的方式和嚴厲的制裁而聲名狼藉。

　　You can make an arbitrary choice.

　　你可以隨便做選擇。

　　The old man became increasingly prejudiced, arbitrary, and senile.

　　他越來越變成一個偏見、固執和獨斷的老人。