Sentence 1: Types A and B were proposed in the 1970s , and the other types were proposed subsequently when the first two proved insufficient to classify ADRs .
Sentence 2: Types A and B were proposed in the 1970 ’ s , and the first types were subsequently proposed when the other two had proved insufficient to classify ADRs .
Question: Do Sentence 1 and Sentence 2 express the same meaning? Yes or No?