英语翻译What does the poster on the wall of the laboratory tell?

英语翻译What does the poster on the wall of the laboratory tell? what does lesson mean in the poster? What does the sign on the wall means?改错 -What does the notice on the wall say? Is there a poster on the wall?怎么回答? There______ a poster and four pictures on the wall ________ write a poster for the Great Wall of China. what does this sign mean on the wall?为什么on the wall在前面,而mean 英语翻译The girl on the wall of herbedroom yesterday. the poster 英语翻译英语翻译提问：The within-laboratory coefficient of variation wa of,what,classroom,is,your,wall,on,the,fron?