Because of toxicity and undesirable side effects , however, these substances are being replaced by synthetic drugs.
但由于具有毒性和副作用, 这些药物渐为合成药物取代.
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Scientists have studied the natural drugs and make synthetic drugs the laboratory similar drugs.
科学家研究得出,自然的药物和在实验室里人工合成的药物很相似.
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