沙门菌在选择培养基SS琼脂上其菌落呈现出无色或其他何种颜色？（）
A.浅红
B.深红
C.微黄
D.浅蓝
E.深灰
参考答案：C
分解因式：a4-a2=______．
用适当的词填空。
1. This is ______ (I) ruler.
2. ______ (he) name is Alan.
3. ______ (she) jacket is red.
4. It's ______ (you) clock.
5. ______ (my) am a boy.
______ (me) English name is Tony.
