冬天的时候，天空看起来比夏天更加灰暗。

The sky looks ___grayer in winter than in summer.

与昨天的讲座相比，今天的演讲显得更加乏味。

Today's presentation was ___duller compared to yesterday's lecture.

随着更多细节被披露，整个事件变得更加模糊不清。

With more details revealed, the whole situation became ___grayer.