题目

已知硅酸盐中硅元素的化合价为+4价，则硅酸的化学式为                    （ ） A．H2SiO4      B．H4SiO3     C．H2SiO3     D．Na 2SiO3 答案：C—I'm sorry，Miss Green.I left my math book at home.—It doesn't matter.Please remember ________ it here tomorrow.A. to take B. to leave C. to bring