The old lady who saw the bus （）into the river phoned the police

The old lady who saw the bus （）into the river phoned the police instantly. 


A、

plunged


B、

to plunge


C、

was plunging


D、

plunge


【正确答案】：D
【题目解析】：

句意：看到公共汽车掉进河里的老太太立刻打电话给警察。see··· do···，看见···做···，用动词原形，此处意为公交车掉进了河里。