I ___________along the pavement yesterday when some strangers came up and asked me the way to the police station.

A．is wandering

B．was wandering

C．has wandered

D．had wandered

鸣叫的青蛙是______性的，它的口角边有一对鸣囊。在青蛙抱对的池塘水面，会发现漂浮着的一片片胶状透明物，这是青蛙的卵块，里面有许多________。