题目

My family moved into our home nine years ago and we spent a lot of time and energy in the yard to get it looking like it does today. We live on a corner and the yard is   41   by a rock wall. We call this area our “rock garden”.Last summer, I found a tiny little   42__in the yard that I could not immediately identify. I knew I didn’t plant it. We   43   to let it continue growing until we could   44   what it was. Weeks passed and as I made my way back to the   45   plant, it appeared to be a sunflower. I decided to treat it with care and   46   the weeds around it.科学研究发现：金星大气层的成分之一是三氧化二碳（C2O3），实验证明三氧化二碳的化学性质与一氧化碳相似．下列关于三氧化二碳的说法中，不正确的是（ ）A．C2O3能使澄清石灰水变浑浊B．C2O3在O2中充分燃烧的产物为CO2C．C2O3在一定条件下能还原氧化铁D．C2O3中碳的化合价为+3价