增加：在缺词处加一个漏字符号（∧）并在其下面写出该加的词。

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。

注意：1）每处错误及其修改均仅限一词；

2）只允许修改10处，多者（从第11处起）不计分。

    On Sunday morning, Jack was painting in the study while the phone rang. He hurried to the phone. He was his workmate, Mike. While they were chatting on the phone, but his little son knocked over painting. Jack rushed back to the study. The painting was on a mess and the baby was crying. He quickly cleared the mess, comforting the baby and then took him out. To his surprises, his wife came back from shopping ahead of the usually time. He was rather embarrassing. He told his wife that it was the cat which caused the disaster.

如图所示电路，电源电压保持不变，闭合开关S₁、S₂，电压表示数为6V，电流表示数为0.6A，断开S₂后，电压表示数变为2V，则R₂的电阻是____ Ω，电源电压分别是____ V。