a follow-up letter的用法和样例：
- You should follow up your letter with a phone call.
- If the attending surgeon has a follow up time table suggestion, it is then better to follow his advice.
- Nevertheless, it continued, there should be a follow up and assessment of the results achieved because resources were scarce.
- Methods CSF NSE level was detected in 58 patients with epidemic encephalitis B with RIA and a follow up study was made in 26 patients.
- Yesterday, we had a follow up audit at your facility. Here we would like to point out both your best practices and areas need to be improved.