many trees --- along the streets every year so the air is very fresh nowa\ plantb\ are plantedc\ plantedd\ were planted请您说明理由好吗?

many trees --- along the streets every year so the air is very fresh nowa\ plantb\ are plantedc\ plantedd\ were planted请您说明理由好吗?
many trees --- along the streets every year so the air is very fresh now
a\ plant
b\ are planted
c\ planted
d\ were planted
请您说明理由好吗?

many trees --- along the streets every year so the air is very fresh nowa\ plantb\ are plantedc\ plantedd\ were planted请您说明理由好吗?
B 每年沿着这些街道都会种上许多树,所以现在空气很新鲜.
树肯定是人种上去的,不可能树自己种,所以此句用被动语态,AC排除
根据every year 可知用一般现在时,排除D
故选B