It is as good as could expect还是It is as good as I could expect?

题目

It is as good as could expect还是It is as good as I could expect?
The plane is captable of two__________ (day) flight.
填days还是days'

答案

是It is as good as I could expect
前后主语不一致,所以不能省略
是days' 名词复数所有格,直接在s后面+ ’