1. A flood occurs every year.
洪水年年发生。
还能这样说：
Flood disaster occurs every year.
There are floods every years.
应用解析：
at the flood 涨潮；在最有利的时候；
in flood （陆地）一片汪洋；
stem the flood 力挽狂澜；
throw a flood of light on sth. 充分阐明；
flood out 淹没
2. The flood water is going down.
洪水渐退。
还能这样说：
The flood water is subsiding.
The flood water is receding.
谚语：
The world is a ladder for some to go up and others to go down.
世界如阶梯，有人上有人下。
3. Earthquakes occur frequently in Japan.
日本时常发生地震。
还能这样说：
In Japan, earthquakes are recurrent.
Japan is a country with frequent earthquakes.
应用解析：
may occur 可能发生，可能在所难免；
occur kill 突然杀死；
sources occur 不是什么新词；
occur for 当；
occur to 想到，想起
4. Sichuan earthquake is once in a blue moon.
四川地震是百年一遇。
还能这样说：
Sichuan earthquake is really a once in a century-time.
Sichuan earthquake is a hundred-year one.
谚语：
The moon is not seen where the sun shines.
小巫见大巫。
5. Our experts predicted that an earthquake was imminent.
专家预言即将发生地震。
还能这样说：
The experts have uttered a prediction that there would be an earthquake.
The experts prophesied that an earthquake was about to occur.
应用解析：
imminent意为：迫切的，危急的，逼近的，即将临头的；目前突出的。
例如：Each country faces the imminent danger of nuclear war.
世界各国都面临着核战迫近的危险。
6. The volcano is in eruption.
火山正在喷发。
还能这样说：
The volcano is erupting now.
The volcano eruption is on-going.
应用解析：
dance on a volcano 在火山上跳舞，大难将至犹自取乐；
sit on a volcano 坐在火山顶上，处境危险
7. The volcano is inactive.
这座火山已进入休眠状态。
还能这样说：
The volcano is in dormancy.
It's a dormant volcano.
应用解析：
lead an inactive life 过蛰居生活；
inactive file 待用文件；
inactive fleet 后备舰队；
inactive reserve 已退役后备队
8. Thousands lose their lives in the disaster.
数千人死于这场灾祸。
还能这样说：
The disaster is the reason for the dead of thousands of people.
The disaster has caused thousands to lose their lives.
应用解析：
lose memory 丧失记忆；
lose one's way 迷路；
lose no time 刻不容缓；
lose one's fear 解除忧虑；
lose balance 失去平衡；
lose one's ground 落伍；失势