radio/radium/radiate/radiation/radio-active/wireless
记忆：
1. radio　[ 5reidiEu ]　n. 无线电通信，收音机 To listen to the English programs on the radio is very helpful in improving our English. 听电台的英语节目对提高我们的英语水平很有帮助。
2. radium [ 5reidjEm ]　音“镭”，具有放射性，　n. 镭 It’s Madam Curie who discovered radium. 是居里夫人发现的镭。
3. radiate [ 5reidieit ]　vt. 放射, 辐射 Heat radiated from the stove warmed the whole room 从炉子里车身出来的热温暖了整个房间。
4. radiation [ 7reidi5eiFEn]　n. 放射, 辐射 The nuclear radiation caused severe pollution. 核辐射引起了严重的污染。
5. radio-acitve 　adj. 放射性的 The soil there proved to be radio-active. 那儿的土壤被证明有放射性。
6. ray [ rei ]　n. 光线，射线 The morning ray came through the window, making the room full of warmth. 晨光从窗口进来，使房间里充满了温暖。
7. wireless [ 5waiElis ]　adj. 无线电的，无线的 Our company is devoted to wireless communication我们的公司致力于无线电通讯。
另类阅读：
Radios are sometime called “wireless,” for they pick up messages without any wires. Radios may have something to do with radiation, but it’s not radio-active at all. No harmful rays radiate from them.