体重超过标准的30%可见于()
A．甲状腺功能亢进
B．肾上腺皮质功能亢进
C．恶性肿瘤
D．活动性结核病
E．1型糖尿病
参考答案：B
（8分）如图所示，电源电动势E＝30 V，内阻r＝1Ω ，电灯上标有“6 V，12W”字样，直流电动机线圈电阻R＝2Ω．若电灯恰能正常发光，求：
（1）电动机输出的机械功率；
（2）电源的效率．
Sandy didn't tell her parents that she was going home because she wanted to give them a _______. [ ]
A. gift
B. call
C. surprise
D. note
