28. GWD31-Q28

Rock
samples taken from the remains of an asteroid about twice

the size
of the 6-nuke-wide asteroid that eradicated the dinosaurs

has
been dated to be 3.47 billion years old and thus is
evidence

of the earliest known asteroid impact on Earth.
     

1)
has been dated to be 3.47
billion years old and thus is

2)
has been dated at 3.47 billion
years old and thus

3)
have been dated to be
3.47billion years old and thus are

4)
have been dated as being 3.47
billion years old and thus

5)
have been dated at 3.47 billion
years old and thus are

C,OR E ???

og 上 sloth 那道用的是date at

这里的答案是date to be