有一线性系统,其输入分别为u1(t)和u2(t)时,输出分别为y1(t)和y2(t)。当输入为1u1(t)+2u2(t)时(1,2为常数),输出应为
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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