The Department of Health has focused on getting what are known as respirator masks. These have filters, which stop a person breathing in some particles in the air.
卫生部重点准备那些带过滤装置的口罩，这种口罩的过滤器可以防止人吸入空气中的一些微粒。
They stop smaller particles, flow more oil and last longer than regular filters.
他们停止了更小的粒子，流更多的石油和最后一个过滤器超过正常。
Equivalent circuits of two proposed electromagnetic stop band filters have been developed. And their parameters have been optimized using this method.
本文对两个新提出的电磁阻带结构滤波器建立了等效电路，并用该方法优化了相应的参数。
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