Hi,
I don't seem to be able to understand a sentence completely..
"A crocodile may go through several thousand during a lifetime of over seventy years."
What confuses me is the "may go through several thousand" - Several thousand of what?
Several thousand of teeth? Yes, teeth. The writer just didn't repeat the word 'teeth'. The sentence before this one was: "Should they lose one of their eight-centimetre-long teeth, a replacement is always ready."
And then, "over seventy years" - Does it mean "in seventy years"? No. 'A lifetime of over seventy years' means 'a life time of more than seventy years'.
Consider 'The price was over $10', meaning it was more that $10.
Best wishes, Clive