小刚为了测量不规则矿石的密度，做了如下实验：

（1）将天平放在________桌面上，移动游码至标尺左端零刻度后，发现指针位置如图甲所示、此时应将横梁平衡螺母向_________侧调节，横梁平衡后进行测量，结果如图乙所示，矿石的质量为__________g．

（2）在量筒中注入15mL水，系上细线后将矿石放入量筒，水面位置如图丙所示，矿石的体积为________cm³．

（3）根据以上数据算得矿石的密度为_________g/cm³．

（4）假如细线的体积不能忽略，所测矿石的密度比真实值__________（大/小）．

根据句子意思及汉语提示，写出所缺的单词。

1. Oh, I have   ▲   (忘) my key in the room, we can't open the door.

2. Though he lives alone, he has a lot of friends and doesn't feel   ▲  (孤独的) .

3. Mrs. White smiled   ▲  (幸福地) when she received a present from her daughter on Mother's Day.

4. As we all have grown up, we should learn to look after   ▲   (自己).

5. Everybody knows the   ▲   (重要性) of doing exercises, but few can keep doing it.