下列关于“原理--应用”的叙述中正确的是（ ）
A．电磁感应现象--电动机
B．漂浮原理--密度计
C．重核裂变规律--氢弹
D．光的直线传播现象--平面镜
A、电磁感应现象的应用是发电机，而不是电动机．故A错误．
B、密度计测量任何液体的密度的时候都是漂浮在液面上．故B正确．
C、氢弹是利用轻核聚变原理制成的．故C错误．
D、平面镜的应用是能改变光的传播方向和成像．故D错误．
故选B
| 阅读理解。 | ||||||||||||||||||
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| 1. Tom' s father is _ . | ||||||||||||||||||
| A. a teacher B. a doctor C. a driver D. an office worker | ||||||||||||||||||
| 2. Jane has __ for breakfast. | ||||||||||||||||||
| A. an egg, an apple and some juice B. some bread, two eggs and a glass of milk C. some bread, an egg and a glass of milk D. an egg, an orange and some bread | ||||||||||||||||||
| 3. Tom has rice, chicken and vegetables for __ . | ||||||||||||||||||
| A. breakfast B. lunch C. supper D. dinner | ||||||||||||||||||
| 4. Jane has supper with her __ . | ||||||||||||||||||
| A. classmates B. cousins C. friends D. parents | ||||||||||||||||||
| 5. Tom has supper __ . | ||||||||||||||||||
| A. at school B. in a restaurant C. in a food shop D. at home |