牙斑如果不清除就会导致牙齿蛀蚀和牙龈疾病。When not removed, plaque causes tooth decay and gum disease.戒指内侧有一层厚厚的锈斑。The tarnish lay thick on the inside of the ring.她比较胖，脸色暗淡、多斑。She was rather fat, and her complexion was muddy and spotty....
On the basis porous carbon , the reactive sintering silicon carbide ceramics were prepared by ihrigizing reaction.以此为基础, 进一步通过渗硅反应,制成反应烧结碳化硅陶瓷.The effect of the sintering temperature on the degrease performance is obviou...