γδT细胞的表现型是（）
A.CD4+CD8+
B.CD4+CD8-
C.CD4-CD8+
D.CD4-CD8-
E.CD2+CD3-
参考答案：D
按照你本人的实际情况回答。
1. Do you like English?
_____________________.
2. What do you think of your English teacher?
3. What does your father do?
______________________.
4. Are you free tomorrow?
5. What do you usually have for breakfast?
下列运算正确的个数是（ ）
①a2+a2=a4；②3x-2xy2=1；③3ab-3ab=ab；④（-2）3-（-3）2=-17．
A．1
B．2
C．3
D．4
