So far, only 39 sequences of the XF hybrid variant have been identified and only in Britain.
到目前为止, 只有 39 个 XF 杂交变体的序列已被识别, 并且仅在英国。
精选英语短文
The first was registered on January 7, and no samples have been found since February 14. The agency concluded that XF was unlikely to be associated with sustained community growth.