The causes of tarnishing gold and silver - plated connectors were studied respectively.分别探讨了接插件镀金和镀银层变色的原因.Bright tin electrodeposits on copper wire are susceptible to tarnishing.铜线材经光亮镀锡后易产生腐蚀变色.Do they not realize thei...
The teacher began to pass out the papers at 8:15.8点15分老师开始发卷.Mary, you do the honours. Somebody has to pass out the presents.玛丽, 你来担任司仪工作. 有人要发奖.Polly is due to pass out from training college at the end of July.波利七月底将从训练...