Richard was very strict with his two daughters them to compete against each other.A. to tr

问题补充：

Richard was very strict with his two daughters,them to compete against each other.

A. to train

B. trained

C. and trains

D. training

答案：

A. to train

B. trained

C. and trains

(答案→)D. training

解析：考查非谓语动词。句意：理查德对他的两个女儿非常严格，训练她们彼此竞争。现在分词表示主语正在进行的伴随性动作，和句子主语是主谓关系，结合语境可知选D。