题目

Everyone wants to have healthy teeth. When you laugh, you will open your mouth and show your teeth. The healthier your teeth are, the【1】( happy) you feel. Why is that? That’s 【2】 your teeth are important in many ways. Take care of them, and they will help to take care of you. Strong, healthy teeth help you 【3】 (grow). They also help you speak 【4】(clear). You can take care of your teeth by doing like these: Brush your teeth【5】 (two)a day, after getting up and before bedtime. And brush all of your teeth, not just the front ones. Spend some time 【6】the teeth along the si有一款手机的主要参数如表所示，问：网络频率：GMS GPRS；900/1800/1900 MHz可选颜色：冰银蓝、Stellar Grey体积：10 0×48×20mm3质量：144g屏幕参数：256色STN彩色屏幕100×80像素34.00×28.00 mm 2标准配置：锂电池（700mAh）（1）这款手机的平均密度是多少？（2）如果用某种塑料做一款是实物体积1000倍的“广告手机”，其质量是96kg（已知该种塑料密度为1.2×103 kg/m3），这个“广告手机”是空心的还是实心的？