有一读者问：如何做这样一道改错题？
(1)A computer is a machine designed to perform work mathematically and store and select information that has fed into it.
标准答案是应在store之前加上to，但我对此抱有怀疑。
不定式连用时，一般只有在表示对比或强调时始须重复不定式记号to，如：
(2)To be or not to be, that is the question. （莎士比亚名句）
(3)It was better to laugh than to cry.
(4)Doctors require hypertension patients to avoid getting upset and reduce to the minimum the vibration of the afterbrain, and especially to avoid falling down. （第二个to avoid显然是为了强调而重复了to）
在其他情况下，一般皆可省去第二个to,如：
(5)I'd like to lie down and go to sleep. （go前省去to）
(6)They are anxious to learn from us and share their experiences. （share 前省去to）
由此可见，上述句（1）的错误并不在于store and select 之前没有to （你的怀疑是有道理的），而在于主动语态has fed。 这个主动语态has fed 显然用错了，应改为被动语态has been fed。
