为了探究影响鼠妇分布的环境因素，在确定研究课题前，首先应该（  ）

删除：把多余的词用\划掉

修改：在错词下画一横线，在其下写上修改后的词

    My grandfather and I enjoy fishing.

    One Sunday morning we go fishing at a lake. We took ours fishing poles and headed for the lake.As soon as we arrived, so we dropped the lines into the water.Before waiting for about half an hour, I was beginning to get impatiently, I wanted to give up, and my grandfather told me to wait a little longer. Finally, there were a sudden pull at the pole and fish was caught. Within the next few minute, my grandfather also caught a fish.

    Felt hungry, we built a fire by the lake and barbecued the fish. It was delicious.

 图甲是某同学探究电流与电阻的关系的实验电路．已知电源电压恒为4.5V，滑动变阻器规格为“20Ω 1A”，可供选择的定值电阻的阻值为5Ω、10Ω、15Ω、20Ω、25Ω和30Ω．

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