设f(t)为连续函数，且
，求f(t)
参考答案：[*] 由f(0)=0知C=2，f(t)=2et-t2-2t-2
— What are you going to do tomorrow?
— I'm not sure. I ____ make a trip to Hangzhou with my girl friend. [ ]
A. may
B. maybe
C. will
D. must
用______材料包装的货物去挪威，在挪威办理货物进口手续时必须提供证明。
A．草类B．旧编织材料制成的麻袋、打包麻布C．塑料D．以上三种
，求f(t)
，求f(t)