【简答题】y'(t)+2y’(t)+2y(t)=f(t),y(0_)=0,y’(0_)=1,f(t)=u(t)
【单选题】They can’t dismiss you just like that. They have to give you a written _____ first.
【单选题】How can the companies cut their cost according to the passage?
A.
They dismiss some employees to save money.
B.
They use temporary labors and cheap labors.
C.
They refuse to pay for the employees' health insurance.
D.
They invest money on marketing campaigns.
【简答题】记∇为差分算子,则下列不正确的是( )。 A 12-∇-∇=∇t t t Y Y Y B2122--+-=∇t t t t Y Y Y Y C k t t t k Y Y Y --=∇ D t t t t Y X Y X ∇+∇=+∇)
【简答题】完成对话。 A: _______ me, Bill. Can you _______ me? I can't find _______ pencil. B: Isn't it _______ your bag? A: No, it _______. B: Please look _______ it under the desk. A: Oh, it is over there. Thank yo...