BDI——虽然作为早期警报指数有用——总是具有不稳定性和夸大性，随交易其升降很大。
The BDI - though a useful early-warning index - is highly volatile and exaggerates apparent ups and downs in trade.
天然除虫菊酯虽然具有理想化学农药的一些特性，但光不稳定性和昂贵的价格限制其大面积使用。
Pyrethrum possesses some ideal characteristics of environmental compatible chemical pesticide, however its photo lability and expensive price limit its broad use in the field.
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