阅读下列短文，按要求完成各题。
One day an American called Simon went to London to visit his friend, Rick. Rick told him that his flat was on the first floor. When he arrived, Simon went straight to the first floor of the building. But he was told that there was no Rick on that floor. Do you know why?
In fact, the British call the first floor of a building the ground floor. The floor above the ground floor is the first floor, which Americans would call the second floor.
The story shows that there are a few culture differences between Britain and America, though the British and Americans both speak English. The British usually hide their feelings. They seldom start a conversation with strangers. For example, on the train the British often spend their time reading newspapers or books. But Americans are quite different. They're more active and easier to talk with.
The British and Americans may use different terms for many things. The British usually use football, eraser and mail while Americans prefer to use soccer, rubber and post.
3C+4D反应中，相同条件下表示该反应速率最快的是 （ ）