填空题 Complete the passage, using the appropriate words. A headache is caused by chemical activities in your brain , ____1_____ ( or /because / but ) the blood and muscles in and around your head. _______2_______( As a result / Therefore / In addition ), some people may carry genes that make them more likely to be affected by headaches. There are some things that may ____3______( treat / examine / cause ) you to get a headache. Consuming alcohol is said to be a common trigger for a headache. Certain food, _____4_____( such / such as / so )processed meat, may also cause headaches. Lack of sleep or poor posture could be another cause. Research has ______5_______ ( show / shown / showing ) that skipping meals and being under stress can give people headaches too