Question

和我们的英语老师相处多么开心啊！

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Answer

What (great) fun/ a good time we are getting on/ along with our English teacher!

【解析】

感叹句结构为What +(a/an)+ adj.+ 名词+主语+谓语部分，“开心”为fun，是不可数名词或a good time；“和某人相处”为get on/along with sb.，故答案为What (great) fun/ a good time we are getting on/ along with our English teacher!