All but one ＿＿ take part in the conference ＿＿ tomorrow.

A．is going to； that is to take place

B．are going to； that is about to take place

C．are going to； that is to be taken place

D．are going to； which is to be held

重79N的正方体铁块静止在1m²的水平桌面中央，求桌面受到的压强为_________．