设f（x）为定义在R上的奇函数，当x≥0时，f（x）=2^x+2x+b（b为常数），则f（﹣1）=（　　）

A．﹣3

B．﹣1

C．1

D．3

You have my word that you shall have the certificate before you _____ this summer.[ ]

A. have graduated

B. graduate

C. will graduate

D. will have graduated