-- The city of Wenzhou looks more and more beautiful. Yes. That’s because lots of trees

问题补充：

-- The city of Wenzhou looks more and more beautiful.

-- Yes. That’s because lots of trees every year.

A. plant

B. are planting

C. are planted

D. have planted

答案：

A. plant

B. are planting

(答案→)C. are planted

D. have planted

解析：句意：温州市看起来越来越漂亮了。——是的。那是因为每年都要种植许多树。结合语境可知下文宾语从句中表示的是客观性的动作，故用一般现在时态。主语是动作对象，故用被动语态，选C。