N95 respirators are designed to protect you from breathing in very small particles that may contain viruses. These types of respirators fit tightly to the face so that air is inhaled through the filter material. N95 respirators should be worn only on...
(一)美国货币 美国货币由美元dollar和美分cent组成,one dollar等于100 cents。其纸币bill有一、二、五、十、二十、五十和一百美元等面值;硬币(coin)有一...