题目

— How long do you think it will be        China sends a manned        spaceship to the moon? — Perhaps two or three years.       A. when         B. until          C. that           D. before 答案：D写出下列反应的离子方程式．（1）用稀硫酸清洗铁锈 （2）硫酸铜溶液和氢氧化钡溶液混合 ．