Things made of plastic are usually_____, but they are _____ to get polluted.[ ]
A. cheap; easy
B. cheap; easier
C. cheaper; easy
D. cheaper; easier
答案:D
Things made of plastic are usually_____, but they are _____ to get polluted.[ ]
A. cheap; easy
B. cheap; easier
C. cheaper; easy
D. cheaper; easier
答案:D