mutation

这种病毒经历了快速的变异，使得疫苗难以生效。

The virus underwent a rapid ___mutation, making the vaccine less effective.

这种果蝇的基因突变导致它拥有了白色的眼睛，而不是常见的红色。

The ___mutation in the fruit fly's genes gave it white eyes instead of the usual red.

这种基因突变导致了植物产生了新的特性。

This genetic ___mutation caused the plant to develop new traits.