硫酸亚铁在工农业生产中有重要用途,也有较高的医用价值。某工厂用铁屑和稀硫酸反应生产硫酸亚铁。将50kg质量分数为19.6%的稀硫酸跟足量的铁屑反应。
(1)试计算生成硫酸亚铁的质量。
(2)人体铁元素摄入不足会引起 。
Tom studies _______. He _______plays with his friends.
—do you exercise? —Hardly ever.
I have ____________ homework to do and I’m _______ tired now.
The problem is _________ difficult ________ students can solve them.
---Why don’t you go out to play, Rose? ---I’m afraid I can’t. I have much homework _______.