下列各句中，没有语病的一句是

I ______ the TV series The Legend of Zhenhuan when mymom made a phone call to me.

This maths problem is_______ easier but______ interesting than that one.

Students ___________ remain in their seats until all the papers have been collected.

The disaster relief funds are already ______ so that people in the earthquake-stricken area can carry out reconstruction work without delay.