核心问题
（1）Play football not only makes us grow up tall and strong but also gives us a sense of fair play and team spirit. (全国高考,98-89) (改错题)
标准答案是将 Play 改为 Playing。这当然是正确的。但是,改为 To play 就是错误的吗?
(2) I was often a little tired after a day's work and watch TV demands very little effort. (同上, 99–88)
标准答案是将 watch 改为 watching, 能否改为 to watch 呢?
词典解答
应当肯定标准答案是正确的。但是，将 Play 改为 To play 和将 watch 改为 to watch 也同样是正确的。标准答案应分别给出 Playing/To play, watching/to watch, 见 infinitive 。