hardest

adj.

困难的( hard的最高级 )；硬的；有力的；努力的

1. The thirtieth math question was the hardest.
   第三十道数学题是最难的。
2. The hardest thing is writing a recommendation for someone we know.
   最难的事情，是为一个认识的人写介绍信。

The hardest known oxide
The Hardest Context-Free Language.
Discovery of hardest known oxide
The hardest constraint problems: A double phase transition
The hardest constraint problems: a double phase transition
Materials science. The hardest known oxide
Priming, Replication, and the Hardest Science
Comment: Educational Research: The Hardest Science of All
Notes on transference: universal phenomenon and hardest part of analysis
Addressing the "hardest puzzle in American pomology:"Phylogeny of Prunus sect. Prunocerasus (Rosaceae) based on seven noncoding chl...