A.
document.getElementById("tb").cells[2][1].style.background-color='
C.
document.getElementById("tb").cells[2][1].style.backgroundColor='
E.
document.getElementById("tb").rows[2].cells[1].style.backgroundColor='
F.
ff0000';G.document.getElementById("tb").rows[2].cells[1].style.background-color='H、ff0000';