Where is my pen ? Have you seen ____?— Oh, sorry. I have taken ____ by mistake.

The number of the students in our school is about nine ____. ____ of them are boys.—I think so.

Tom was sad because he did _______ in the math exam.

He built a telescope _____ he could study the skies.[ ]

Some students often drop litter carelessly in our school. What can we do?- We can _______ some signs to remind them not to do that again.