1 Thank you 句子主干,谓语+宾语（主语I被习惯省略了）
for your letter dated 15 March regarding this year's staff outing to Margate（介宾结构做原因状语）.状语内部还要再细分析吗?
2 We 主句主语
cetainly 副词做状语
appreciate 主句谓语
that you have retained last year's price for this outing.宾语从句,从句内部要不要再分?
3 All our employees 主语
are very much looking forward to 谓语
our day trip,宾语
and 连词,另起一句
we 主语
are sure 谓语（系表结构）
your coaches will ensure a comfortable journey.宾语从句
翻译整理如下：
1.感谢您于3月15日那天写信邀请我们把今年的员工福利旅行安排到Margate
2.我们会很高兴,如果今年不涨价.
3.全体员工都很期待此次旅行,我们相信你们的教练会确保此次旅行圆满舒适.