PLEASE HELP, this is for science water molecules

Which flexible structure that supports the nerve cord and led to the backbone

Which sentence is an example of a strong conclusion to an autobiography? a. i stayed after school three days in a row to practice onstage in the auditorium. b. i knew i would have to practice all week to memorize my dance for the recital. c. after the recital was over, i knew practicing was worth it, and i was looking forward to my next big challenge. d. on opening night, i danced in front of a packed auditorium.

Which of the following happened during the precambrian era? the first prokaryotic cells the first eukaryotic cells development of photosynthesis all of the above