-- ____ is the letter from? --From my aunt in London.
— Look at the boy playing basketball on the ground. Is it George?— It ________ be him. He told me he would play basketball after class, but he’s not sure.
The thing that matters is not whether you fail or not, ________ whether you try or not.
Lanzhou is the only capital city that the Yellow River, the second ________ river in China, passes through.。
Only when the work is done ________ be able to go back home.
In this exam, you’re asked to write a composition of about ________.