传播效果的“子弹论”出现在20世纪初至30年代末的原因主要有哪些？

—Have you seen Tony recently?  

—No, but I ______ dinner with him on Sunday.  [ ]

A. would have  

B. have had    

C. have been having    

D. am having

We went to the Lincoln Memorial yesterday, ___, not surprisingly, was crowded with visitors from all over the world.

A．where

B．which

C．that

D．when

如图所示，质量为m的物体A在竖直向上的力F（F＜mg）作用下静止于斜面上．若减小力F，则（　　）

A．物体所受合力变小

B．斜面对物体A的支持力不变

C．斜面对物体A的摩擦力变大

D．斜面对物体A的摩擦力可能为零

流动性最强的货币类型是( )。

A．M₁

B．M₂

C．活期存款

D．M₀

简述孔子的教育思想。