1·Insecticide-treated bed nets, millions of which have been sold or given away in Africa in the past decade, have a long-acting repellant, permethrin.
过去十年，人们在非洲售出或分发了数百万经杀虫剂处理过的蚊帐，这种蚊帐含有一种长效驱虫剂：合成除虫菊脂。
2·Therefore, it is not surprising that the origins of mosquito repellant are from long ago.
因此，驱虫剂的起源悠久实不令人意外。