Isolation may cause heart disease and shorten life span.
查看答案
Loneliness increases the risk for rea physical pain.
A. 对
B. 错
The simple act of saying "hello" can enhance our immune system.
A. 对
B. 错
The news report mainly tells us how to get rid of loneliness.
A. 对
B. 错
cosx的全体原函数为（ ）
A. cosx+c
B. sinx+c
C. -cosx+c
D. -sinx+c
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