Things made of plastic are usually _______, but they are _______ to get polluted.

A．cheap; easy

B．cheap; easier

C．cheaper; easy

D．cheaper; easier

（）的字形有4类特征：圆形、方形、三角形、特殊形

A.汉字

B.拉丁字母

C.希腊文字

D.英文