It was in the street _______ I met one of my friends yesterday.
He slipped(溜进) into the classroom without ___________.
This special strain of rice makes _________ possible to produce one third more of the crop in the same fields.
---Is that the small town you often talk about?---Right, just the one ______________ you know I used to work for three years.
Although the first part of the book is easy, the rest ______.
----Where are you now?----Well, I have arrived at _______ is called “the West lake”.