'Turn' in the Bible

So I went to the angel and asked him to give me the small scroll. "Take it and eat it," he told me. "It will turn bitter in your stomach, but it will be as sweet as honey in your mouth."

These witnesses have authority to close the heavens in order to keep rain from falling while they are prophesying. They also have authority to turn bodies of water into blood and to strike the earth with any plague, as often as they desire.