—Where is the cat?
—It's _____ the chair. [ ]
A. in
B. at
C. over
D. under
答案：D
人说话时声带在______，拉胡琴时琴弦在______．这些现象说明，一切发声的物体都在______．
下列实验操作正确的是[ ]
A.
B.
C.
D.
