什么术语是用来感受比情绪更弱并经常缺乏背景刺激的情感？（）
A.情感
B.认知
C.行为
D.心境
E.情绪
参考答案：D
用E(θ)表示活塞流反应器的停留时间分布密度函数，则E(1)等于( )。
A．(0.5
B．(∞
C．(0
D．(δ(0)
The environmental group hopes ______ the forest to its original condition by the end of the decade.
A．having restored
B．to have restored
C．to be restored
D．to have been restored
