GWD32-Q4 rock samples taken from the remains of an asteroid about twice the size of the 6-mile –wide asteroid eradicated the dinosaurs has been dated to be 3.47billion 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 3.47 billion 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 答案选3。看后面的old,表示samples的'年龄'已经是3.47b年;如果用5的dated at,至少old就不该要,只能说'at'在哪一年而不能说在哪一年old;如果要表达‘多少年前’这个概念,应该用before和完成时连用,相应地,at也该改为from: have been dated from 3.48 billion years before |