While he was ______ about in the street, Mary came up to him.
His writing is so confusing that it's difficult to make out ________ it is he is trying to express.(2011·安徽,33)
It is by no means clear ________ the president can do to end the strike.(2012·新课标全国)
________you said at the meeting describes a bright future for the company.
From space, the earth looks blue.This is ________about seventy-one percent of its surface is covered by water.
The only way to succeed at the highest level is to have total belief ________ you are better than anyone else on the sports field.