诱导B细胞产生特异性IgE抗体的细胞因子（）
A.IL-2
B.IL-3
C.IL-5
D.IL-1
E.IL-4
参考答案：E
用所给词的适当形式填空。
1. He has a friend _____ (call) Jack.
2. How many _____ (month) are there in a year?
3. The play is so _____ (wonderfully).
4. People in the _____ (western) celebrate Halloween every year.
5. The little boys like soft _____ (drink).
，对于其它的x，f(x)满足f(x)+k=2f(x+1)，求常数k的值，使f(x)在x=0处连续．
，对于其它的x，f(x)满足f(x)+k=2f(x+1)，求常数k的值，使f(x)在x=0处连续．