英语语法分析

But a comparison with similar drugs showed propoxyphene was more dangerous.

但是与类似的药物相比丙氧芬更加危险。

Since 1978, the FDA has received two requests to remove propoxyphene from the market.

自1978年以来，FDA已经收到了两次从市场上撤销丙氧芬的请求。