A:①②
B:①③
C:③④
D:②④
人的消化系统中,消化和吸收的主要器官是( )
如图所示,在一块平板玻璃上放置一平凸薄透镜,在两者之间形成厚度不均匀的空气膜,让一束单一波长的光垂直入射到 该装置上,结果在上方观察到如图所示的同心内疏外密的圆环状干涉条纹,称为牛顿环,以下说法正确的是( )
(____)1. Let me clean the window.
(____)2. Look! The bird is on the light.
(____)3. There isa picture on the wall.
(____)4. The book is near the computer.
(____)5. The bag is on the chair.
A. B. C.
D. E.