小麦和青蛙个体发育的起点是[ ]
A．受精卵
B．种子或刚孵出的小蝌蚪
C．成熟的卵细胞
D．成熟的精子
答案：A
____ the telephone number several times, but he couldn't learn it by heart. [ ]
A. Having told
B. Having been told
C. Although he had been told
D. He had been told
呼吸性碱中毒（）
A.pH下降，HCO-3下降
B.pH升高，PaCO2升高，HCO-3下降
C.pH下降，PaCO2升高
D.pH升高，PaCO2下降，HCO-3下降
E.pH升高，HCO-3升高，BE升高
