Man in the 20Th Century: Traveling in Africa

After a sudden death, when he woke up, Zheng Siming found that he was in the body of a child. He actually came to a deserted island that didn't exist in the world at ordinary times. Facing Gaul's large-scale military recruitment, he awakened the item recovery system! [Hey, the host has recovered the battleship, and the reward is 20 million points] Convert the credit into real currency and I'll buy, buy, buy! State-of-the-art steel production technology? Purchase! The most advanced tank manufacturing technology? Purchase! The most cutting-edge scientific and technological knowledge? Purchase! Atomic bomb? Sorry, I know how to make it! Europa: No, buddy, how did you go from a small border place to a regional power? America: I'm not a buddy, why do I always suffer at your hands? Look at a deserted island and learn how to advance science and technology. Starting from scratch, an agricultural society has made great strides to the civilization after the second industrial revolution.