var node = document.DocumentNode.SelectNodes("//tr[not(@class)]/td[@style='width:1%;' or @class='coef' or (@class='left' and .//a)]");
var node = document.DocumentNode.SelectNodes("//tr[not(@class) and count(td) = 18]/td[@style='width:1%;' or @class='coef' or (@class='left' and .//a)]");