Given that i = 100 sin（314 t － 30°）A, u = 311sin（314 t + 60°）VFind the phase difference between u and i（）
A. – 90°
B. 30°
C. – 30°
D. 90°
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As medical knowledge__, people’s beliefs change（）
A. involves
B. evolves
C. resolves
D. dissolves
芦荟的功效是（）
A. 泻下、攻积、杀虫
B. 泻下、软坚、清热
C. 泻下、解毒、活血
D. 泻下、清肝、杀虫
具有泻下、软坚、清热作用的药物是（）
A. 大黄
B. 番泻叶
C. 芦荟
D. 芒硝
The police have__ an investigation into the incident（）
A. released
B. launched
C. sent
D. proceeded
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