Răspuns :

1) Yesterday we learned how life appeared on our planet.

2) Sciencists think that 4.6 billion years ago the Earth represented a swirling mass of boiling hot rocks and gases.

3) Jason, what are you doing at such a late hour? - I am typing the results of my experiment.

4) If the matter wasn't urgent, I wouldn't have asked you to come today.

5) Peter wishes he knew more about this subject.