Can you make sure of （ ） the visitors right now?
（A）a number of
（B）the number of
（C）an amount of
（D）the amount of
We need three more （ ） to cook chips.
（A）potato
（B）potatos
（C）potatoes
（D）potatoss
How wonderful! The （ ） is made of （ ）.
（A）house; glass
（B）house; glasses
（C）houses; glass
（D）houses; glasses
