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参考解析：
刷刷题刷刷变学霸
举一反三
【单选题】Losing Weight Girls as young as 10 years old are dieting and in danger of developing unhealthy attitudes to weight, body image and food, a group of Toronto researchers reported Tuesday. Their study of...
A.
had unhealthy attitudes to weight.
B.
were overweight.
C.
were on a diet.
D.
had healthy weights.
【简答题】电压源型逆变器的主要特点有哪些？
A.
直流侧为电压源或并联大电容
B.
输出电压为矩形波或矩形波的一部分，输出电流因负载阻抗不同而不同
C.
逆变桥各臂并联反馈二极管
D.
只能采用180°导电方式（方波逆变）