- Which medicines should you take for cough? (治療咳嗽應服用哪種藥物？) (正)
- Which medicines should you take against cough? (誤)
解說：For 在此意為「為了 (治療)」(= in order to cure)，而 against 意為「預防 (疾病)」。因此，當疾病的前面給的是治療該疾病的藥物或措施時，介系詞須使用 for，不可使用 against。例如：
- The doctor treated him for epilepsy. (醫生治療了他的癲癇) (正)
The doctor treated him against epilepsy. (誤) - Do you have medicine for a cold? (你有感冒藥？) (正)
Do you have medicine against a cold? (誤) - A good diet and lots of exercise can protect against some kinds of illnesses. (良好的飲食和大量運動可預防一些疾病) (正)
- This is a vaccination against hepatitis B. (這是 B 型肝炎疫苗的接種) (正)