when was the earliest use we know about for concrete???

Answer: about 150 BC
Question: first person to cross niagara falls on a tightrope?

Answer: Nikolas "Nik" Wallenda
Answer this question: where is the human population growing the least??

Latvia
Q: how many times have we been to the mon?A: numerous unmanned landings
Input: when was the first king kong movie made?

Output: 1933
Answer this question: why are the reactions of the calvin cycle called light-independent reactions??
fixation