a. not capable of being foretold
s. unknown in advance
a. 不可预知的
1. The weather in this region is very unpredictable.
这个地区的天气非常不可预测。
2. His moods can be quite unpredictable at times.
他的情绪有时可能非常不可预测。
3. The stock market is often unpredictable, making it hard to invest.
股票市场常常是不可预测的，这使得投资变得困难。