the last or most difficult challenge or area of exploration
最后或最艰难的挑战或探索领域 (zuìhòu huò zuì jiānnán de tiǎozhàn huò tànsuǒ lǐngyù)
"For many scientists, space remains the final frontier."
"对许多科学家来说，太空依然是最后的边疆。" (duì xǔduō kēxuéjiā lái shuō, tàikōng yīrán shì **zuìhòu de biānjiāng**.)
feeling nervous or anxious
to collect things together
to have something as the main point or reason
to sell shares of a company to the public for the first time
Officially stated and reportable
honest and straightforward; without cheating
