把一个长6厘米,宽5厘米,高4厘米的长方体木块锯成两个小长方体,表面积至少增加____平方厘米,至多增加____平方厘米。
Christmas is my favourite 1. On Christmas, my family 2 my aunt,uncle and cousin to our house. We 3 gifts to each other. I give my cousin a 4 gift. We sing the Christmas 5 together. I think we are very happy.
如图是电源电压恒为220V的电热烘干箱的基本电路图,S是双掷开关,R1是发热电阻,定值电阻R2为110Ω,当S接“2”时,R1的电功率是110W,试求: