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 window is dirty.—I knowIt ______ for weeks

In the factory, the helmets the workers wore varied _____ color according to their different posts

The most important words in this sentence have been ______, so it doesn’t make any sense．

by the thought that she wassuffering a heart attack, she screamed for help