1. take a chair（取把椅子）坐下
Won’t you take a chair?
怎么不坐下呢？
Take a chair, please.
请坐。
Tom took a chair and began to sing.
汤姆坐下来开始唱歌。
Even when he came home, he would take a chair outside and just read。
偶然回家，他也总是坐在外面的椅子上，埋头看书。
Take a chair please and let’s do homework together.
请坐下，我们一起做作业吧。
2. take the chair
主持会议或做主席，委员长；开始开会
She takes the chair in all our meetings.
她主持我们所有的会议。
I took the chair at a meeting some time age.
前些日子我主持了一次会议。
He frequently takes the chair and is a very bad chairman.
他经常主持会议，但却是一个很糟糕的主席。
Tom will normally take the chair at such meetings.
汤姆通常会主持这样的会议。
Our proposal is that somebody neutral takes the chair.
我们的建议是让某位中立人士当主席。
Tom will take the chair at the next meeting.
下次会议将由史密斯先生主持。
Mr．Li takes the chair today．
今日是李先生当主席。
另外，hold the chair却表示担任教授或系主任一职，例如:
She holds the chair of chemistry in the university.
她是大学的化学系主任。
He holds the chair of philosophy at Oxford.
他是牛津大学哲学系的系主任。
He has been appointed to the chair of sociology at Southampton University
他被任命担任南安普敦大学的社会学教授一职。
He was elected chair of the city council.
他当选为市议会主席。