岩石圈是指 （   ）

删除：把多余的词用斜线（\）划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

    I hardly remember my grandmother. She used to holding me on her knees and sing old songs. I was only four when she passes away. She is just a distant memory for me now.

    I remember my grandfather very much. He was tall, with broad shoulder and a beard that turned from black toward gray over the years. He had a deep voice, which set himself apart from others in our small town, he was strong and powerful. In a fact, he even scared my classmates away during they came over to play or do homework with me. However, he was the gentlest man I have never known.

小金自学了电学，知道了欧姆定律。他想用实验来欧姆定律所表述的“通过导体的电流与这段导体两端的电压成正比”的结论，于是找了实验器材：电压表、电流表、电源、滑动变阻器、开关各一个，若干定值电阻、导线。请你利用这些器材帮他设计一个验证此结论的实验方案。

半折= ____%      

念去去，千里烟波，____。