他生病了该怎么说英语

If someone is sick, you can say "He is sick" or "He is not feepng well." You can also say "He is under the weather" or "He is feepng unwell." If you want to be more specific about the illness, you can say "He has a cold," "He has the flu," "He has a fever," etc. For example:

"He has a terrible cold and has been sneezing all day."
"He has the flu and has been bedridden for the past few days."
"He has a fever and has been feepng very weak."