Когда пишется DO а когда , Does?

helped "the quests" to choose "the wine" 4."Mother" asked "Mary" to wash "the dishes"

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Professor of Emory University in Atlanta , Georgia, and founded the Carter Center. The Center addresses national and international issues of public policy. The aim of the Carter Center was to resolve conflict , promote democracy, protect human rights and prevent disease and other problems. Through the Global 2000 programme , the Center began advancing health care and agriculture in the developing world. Jimmy and Rosalynn Carter volunteer one wet a year for Habitat for Humanity, a nonprofit organization that helps needy people in the United States and in other countries renovate and build homes for themselves. He was awarded the Nobel Prize for Peace in 2002.

Dear Robert,
Thank you for your letter, we arrived home without accidents. On the way we stopped twice to take pictures for memory. I really liked your city. It is very quiet sometimes it seemed to me that there are no other people. Most of all I remember how we went with your father on a hunting trip. Thank you for all that you and your family did for us. I really hope that you come to us for the new year, I have already started to plan a route where we should go.
Best wishes
Igor.

И когда пишется This, а когда These?

(they/your parensts/ your brother) like pop music? Yes, ... do.3) Do (Rita/Max/you) study English at scool? Yes, ... do.4) Does ( your mother/ they/ your classmates) speak English well? Yes,...does.5) Do (Denys/Helen/ you) do grammar exercises every day? Yes,...do.6) Does (children / you/ your cat) like fish ? Yes,...does.