转基因食品都存在安全性问题，因此不能食用。

I can see a spoon.

如图，平行四边形ABCD的对角线交点是O，则下列等式成立的是（    ）

根据句意，用所给动词的适当形式填空。
(1)By the time he left college, he ____ (get) much working experience because of his part-time job.
(2)John, like other children who have no parents,____  (take) good care of in our country.
(3)We should wash hands properly ____  (fight) against H7N9 virus.
(4)Look! There are so many kites____ (fly) in the sky.
(5)If you want to improve your English, you should practice____ (speak) it as much as possible in and out of class.

如图1所示，已知小灯泡L上标有“6V 3W”字样，R₀=20Ω，滑动变阻器R的最大阻值为100Ω。求：