e dropped ________ “s” in the word “acros”—Oh, ________ letter “s” should be doubled like this “across”

’t think he is fit for the job, ______——Why do you think so

Tsinghua University, ______ in 1911, is home to a great number of outstanding figures.

_______ men are greedy, _____ is never peace [ ]

How often do I need to feed the birds—They ________ food every day，or they will behungry.