Answer;
The Huronian Supergroup <span>is </span>particularly<span> exciting and </span>interesting<span> because, by chance, these </span>rocks<span> were laid down at a period when the atmosphere underwent a transition from containing no free oxygen to containing at least some free oxygen.”
</span> Explanation;
The Huronian
Supergroup, a massive
formation of rock laid down
gradually between about
2.5 billion and 2.2 billion
years ago, precisely the
period when oxygen
began to accumulate in the
atmosphere. The Huronian Supergroup is 10 or 11
kilometers (six or seven
miles) thick and extends well below ground
The way you know the subject of the sentence is plural is because it takes a plural verb. You can see that the subject of the sentence is <em>the ova </em>(plural for of Latin word <em>ovum</em>, <em />meaning egg cell), and the verb it takes is <em>undergo </em>(plural)<em>, </em>and not <em>undergoes, </em>which would be singular.
Answer: By the time they came, we had finished our dinner.
Came is past tense, so I would assume it would be had finished
Iambic pentameter could be the poem you are looking for
I want to say waterings but im not too sure