一条马路两旁各种上9棵树，一共种树多少棵？0U+@5r;U+B*m4G.N7^(h(d
算式：提示+C5M2Y/f'\:I0U+@5r;U+B*m4G.N7^(h(d
答：一共种树(O9F-l+E,G6c+J/J9M5c5b4x:y+y9S*[0f9[棵。0U+@5r;U+B*m4G.N7^(h(d