若关于x的一元二次方程ax2+（2a-1）x-2=0 的两根相等，那么a等于（ ）
A.-0.5
B.0.5
C.0.5或-0.5
D.-0.5或0
答案：A
Susan Jones was at the bus stop well on time to take the 7:01 bus, but she had to miss her breakfast to do it.
A．catch up with
B．catch
C．run up to
D．be catching
静力压桩法与锤击沉桩相比具有施工无噪声，无振动，沉桩速度快等优点。
