a. 无瑕疵的, 不锈的【机】 不绣的, 污染的

dot/dotted/spot/stain/stainless/point
记忆：
1. dot [ dCt] n. 点, 圆点 vt. 在. . . 上打点 Campfires, like red peculiar blossoms, dotted the night. 营火象红色的、别致的花朵点缀着黑夜。
2. dotted [ 5dCtid ] adj. 有点的，虚线的 You can draw a dotted line to help your thinking. 你可以画一条虑线来帮助思考。
3. spot [ spCt ] A mark on a surface differing sharply in color from its surroundings; a stain n. 班点, 污点, 地点, 场所, 现场 n. 沾污 vt. 认出, 发现 Hitting the high spots, we gained little during the trip. 走马观花，我们一路没有什么收获。
4. stain [ stein ] To discolor, soil, or spot n. 污点, 瑕疵 There is no stain in his fame. 他的名声很好，没有污点。
5. stainless [ 5steinlis] adj. 纯洁的, 无瑕疵的, 不锈的 The pot is made of stainless steel. 这锅是用不锈钢做的。
6. point [pCInt] n. 点, 尖端, 分数, 要点 vt. 指 Pointing out that I was wrong, he gave me some advice. 他指出我错了后，给了我一些建议。
另类阅读：
On spot he pointed at some black dots forming a dotted line on the machine. They were stains! The machine was not made of stainless steel as it had been exclaimed!