You can describe something as unstable if it is likely to change suddenly, especially if this creates difficulty or danger.
近义词
fragile , volatile , unsettled
双语例句
例： The situation is unstable and potentially dangerous.
情况不稳定，可能会有危险。
例： After the fall of the Prime Minister in 1801 there was a decade of unstable government.
1801年首相倒台之后，政府经历了十年的不稳定时期。