问题补充:
Every year lots of trees to make our country more beautiful.
A. is planted
B. was planted
C. are planted
D. were planted
答案:
A. is planted
B. was planted
(答案→)C. are planted
D. were planted
解析:句意:每年都要种许多树来让我们的国家更美丽。结合语境可知本句描述的是经常性动作,故用一般现在时态,主语lots of trees为复数形式,选C。