1.let's welcome…让我们欢迎……
Let's welcome him with warm applause.
2.it's my pleasure to…很开心做某事
It's my pleasure to have the chance of studying with you.
3.the dean of………的主管
Professor Smith is the dean of the English Department in Xinhua University.
4.be sure to do sth.确定做某事
We are sure to benefit from Prof.Smith's lecture.
5.it's very kind of you to do sth.你做某事真是太好了
It's very kind of you to give me such a chance.