什么时候在观测记录簿记录MIFG、BCFG、PRFG？什么时候在METAR或SPECI报中编报这些天气现象？

The US Food and Drug Administration (FDA) is taking steps to protect the country’s blood supply. People give blood to the centers, where it is kept until it is needed for medical purposes. The FDA has provided new rules for the blood centers. The government agency says new rules are designed to improve the blood supply system. The new rules call for blood centers to develop more ways to make sure their work is done correctly. These rules are another way to help keep the blood supply pure. A leading concern is that someone with AIDS virus might give blood to a blood center. For this reason, there are tests to find out if blood contains viruses that cause AIDS and other disease. Each year blood transfusion has saved millions of lives, however, if there is no secure blood, it’s increasingly risky for the recipient of blood to be infected with HIV.