他的指示是我收到过最清楚的。

His instructions are the ___clearest I've ever received.

这条路是最畅通的，没有任何障碍物。

This path is the ___clearest one with no obstructions in sight.

这块水晶是我见过最清澈的。

This crystal is the ___clearest one I've ever seen.

他脸上的表情是他感到困惑的最明显标志。

The ___clearest sign of his confusion was the expression on his face.