单项选择题
A．they are following a trail of something that smells good to them B．they are returning to their families C．they have been trained to work with other animals D．they do not know a movie actor is nearby
A．Elephants can be graceful. B．Tigers are too dangerous to be trained. C．Animals which are natural enemies can be trained to live together. D．Animals can become interested in their tricks.
A．faster than other horses B．smaller than other horses C．more suspicious than other horses D．more nervous than other horses