原文：We’ve known about it for many decades now, but flu experts ar

原文：We’ve known about it for many decades now, but flu experts are still involved in a full-time race to keep up with the virus as it mutates.
译文：我们早在几十年前就发现了它，因此流感专家们需要全力与时间赛跑，以便跟上流感病毒变异的速度。
【正确答案】：
改译：虽然我们早在几十年前就发现了它，可是流感专家们仍在全力与时间赛跑，以便跟上流感病毒变异的速度。