英语问题(很简单，但请说明理由!)

1 his speech is easy to understand
be +adj. +to do 做……是……的
be easy to do sth 做某事是容易的
2 he stood up,said say something and went out.
三个连续的动词，时态、形式都一致
3 有没有prefer do to do?
没有
只有以下：
prefer doing to doing
prefer do rather than do
prefer sth to sth
prefer sb to do sth

understood 容易被理解
said 要和stood以及went一致
没有

1 to understand.
因为easy to do 是一个词组，是说某事容易做。
2 said
三个动作是并列的，都用过去时。
3 prefer to do (动词）
或者prefer ...（名词）to ...（名词）