The house 【will be将来时时态信息】 very cold.Make sure ——the heater.
A.you will light B.you light C.for lighting D.lighting
选B.
这里考查 make sure (that) sb do /have done sth 确保要做某事/已经做某事【多用一般现在时或现在完成时.】
句意：房子里会很冷.务必打开加热器.