We are learning English, but how can we learn English well ? A student can know a lot about English, but maybe he can't speak English.
If you want to know how to swim, you must get into the river. And if you want to be a football player, you must play football. So, you see, you can learn by using it. You must listen to your teacher in class. You must speak English to your classmates every day and also you must write something in English. Then one day you may find your English very good .

25＋17＝42

46＋25＝____

67＋23＝____

 如图为元素周期表第4周期的一部分．据此判断下列说法中错误的是（　　）