The reason why he was late is ______ he got up too late.

Math is too difficult. I want to give it up. —Please don’t. Nothing is _________if you put your heart into it.

”It’s five forty-five”means(意思是)”It’s ___________.”

Excuse me. You shouldn’t smoke here. Look at the sign “NO SMOKING HERE”.–Sorry, I ________ it just now.

A lot of scientists believe that women’s sense of smell is better developed than ____ of men.