[jQuery] how to select all first td's inside all <tr> in a table

[jQuery] how to select all first td's inside all <tr> in a table


I have a table that contains several <tr>, all of them look like
this.
    <tr>
        <td>20-04</td>
        <td>459</td>
        <td>559</td>
        <td>659</td>
        <td>439</td>
        <td>519</td>
        <td>599</td>
        <td>424</td>
        <td>489</td>
        <td>554</td>
    </tr>
    <tr>
        <td>27-04</td>
        <td>506</td>
        <td>606</td>
        <td>706</td>
        <td>486</td>
        <td>566</td>
        <td>646</td>
        <td>471</td>
        <td>536</td>
        <td>601</td>
    </tr>
One of the things that I would like to do is add the class "date" to
the first td that exists after a <tr>.
I came up with this -> $("#prijslijst-appartement tr td:eq
(0)").addClass("date"); , but that doesn't really do what I thought It
would. It only adds the date class to one td, and it ignores all the
other <tr> in the table. What I was hoping it would do is finding all
<tr>, and then add the date class to the first <td> in all the <tr> in
the entire table.
You can see the example here -> http://tijmensmit.com/dev/td/prijslijst.html.
The one with the date class on it has the pink border around it.
Its not only the first <td> which I should target, the 3th, 6th and
9th <td> within each <tr> should also be given a different class.
What would be the best way to do this, and to make sure it looks in
all <tr> in the entire table, and not stops after the first one?
Thanks,
Tijmen