重度精神发育迟滞的智商为（）
A.<30
B.35~49
C.20~34
D.20~30
E.<20
参考答案：C
看图读句子，在后面的括号中打“√”或“×”。
( ) 1. Show me your eraser.
( ) 2. Show me your pencil-case.
( ) 3. Go to school.
( ) 4. Carry your bag.
( ) 5. Show me your bag.
( ) 6. Close your book.
什么是转子惰走时间？
Show me your eraser. 
Show me your pencil-case. 
Go to school. 
Carry your bag. 
Show me your bag. 
Close your book.