A: Three minutes.
In the first minute, fry two cakes first;
In the second minute, turn a cake upside down, take out another cake and put in a new cake;
In the third minute, take out a cake fried on both sides, turn the other cake over, and then put the cake just fried on one side in.
2. Q: The seawater in a certain place 1000 kg contains 3 kg of salt. 1 kg of seawater is how many kg? 10 kg of seawater?
Answer: 3 ÷ 1000 = 0.003 kg.
3. Q: In our daily life, we often use a kind of transportation-bicycle, whose wheels are round. Do you know why? Can you briefly talk about why the axle should be placed in the center of the wheel with relevant knowledge?
A: In order to ride smoothly.
The distance from the axle center to the ground is constant, so the wheels are circles with the axle center as the center, so the wheels of bicycles are all made into circles, and the axles should be placed in the center of the wheels.