氙灯的光谱分布与太阳光谱相似。
参考答案：对
___________harder, he would have succeeded in the college entrance examination
A He worked B He had worked C Had he worked D Did he work
19世纪上半期，世界上最强大的资本主义国家是 [ ]
A、中国
B、美国
C、法国
D、英国
ed D Did he work