下列计算正确的是[ ]
A．a2+a2=a4
B．a5a2=a7
C．（a2）3=a5
D．2a2﹣a2=2
答案：B
The goods are being prepared for immediate delivery and will be ready for（）
A.packed
B.shipment
C.accept
D.agreement
地下水含水系统
