用所给词的适当形式填空。每词限用一次。

rise   drive   disappear   turn off   improve

1. When it’s 8:30 p.m. on the last Saturday of March every year, lights ________ around the world and it keeps for an hour to remind people to protect the earth.
2. Mr Li said he ________ nearby when Flight MU5735 fell into the mountains in Guangxi last month.
3. —What’s your opinion about this problem?
—Well I think the tigers ________ unless we take action at once.
4. The sea level ________ by 1.31 mm each year from 1900 to 2015.
5. In China, the living standards of hundreds of millions of people ________ during the past 40 years.