—Hi, Johnson, any idea where Susan is?  —It’s class time, so she          in the classroom now.

（2014年北京市西城区高三5月二模试题）28. It was unusual that such close neighbors ______ not know one another. 

I tried to call on you last week but your dog simply ____ not let me come through the gate.

John ___ be a basketball player.He’s much too short.

 I ________ through that bitter period without your generous help.(2011·陕西)