题目

已知角的顶点与原点重合，始边与轴的非负半轴重合，它的终边过点,=______． 答案：【答案】【解析】由题可得，，代值计算即可。由题可得，When the H1N1 virus____ at first in Mexico, no one had the least idea that it would spread so rapidly throughout the world.A．broke offB．broke downC．broke outD．broke away