Speaking of all the songs he has written,I think this is probably his ____ one. [ ]

At themeeting they discussed three different ______ to the study ofmathematics.

As a student, I can’t afford ________ a new mobile phone.

Did Linda have a good time in Beijing——Yes．She enjoyed__________verymuch．

ount of fuel supplies being finite and manypeople being wasteful, we will have to install ________ solar heating device inour home.