Query parametriche con LINQ to Entities

string sql1 = string.Empty;
if (par1 != string.Empty) sql1 = " AND par1='" + par1 + "' ";

string sql2 = string.Empty;
if (par2 != string.Empty) sql2 = " AND par2='" + par2 + "' ";

string sql3 = string.Empty;
if (par3 != string.Empty) sql3 = " AND par3='" + par3 + "' ";

string sqlLimit = string.Empty;
if (n > 0) sqlLimit = " LIMIT 0," + n);

string sqlAscDesc = " DESC ";
if (AscDesc != string.Empty) sqlAscDesc = " " + AscDesc + " ";

string sqlOrderBy = "ORDER BY campo1 " + sqlAscDesc;
if (orderby != string.Empty) sqlOrderBy = "ORDER BY " + orderby + sqlAscDesc;

string sql = "SELECT * " +
                         "FROM tabella " +
                         "WHERE 1 " + sql1 + sql2 + sql3 +
                         sqlOrderBy +
                         sqlLimit;