By that time I was nervous because there were too many unpredictable things happening.

unpredictable 是由前缀 un-（表示"不、非"）加上形容词 predictable（可预测的）构成的形容词。predictable 来自动词 predict（预测），predict 由前缀 pre-（"预先"）和词根 dict（"说"）组成。 unpredictable 意思是"无法预测的、难以预料的"，形容事情发展超出预期或无法提前判断。