题目

Finland is perhaps the most beautiful and mysterious（神秘的） country of Northern Europe. Two-thirds of its surface is covered with thick forests and among them lie lakes, connected with rivers and canals. The northern part of this country is inside the Arctic Circle, where almost no trees can grow because of its cold weather and the people use their deer for transport, clothing and food. The Finnish history began in the Middle Ages. In about 1155, Finland was conquered(占领) by its western neighbour Sweden. After a period of rule by Denmark in the 14th century, the Swedes won b 下列说法错误的是(     )。 A．含有共价键的化合物一定是共价化合物   B．在共价化合物中一定含有共价键 C．含有离子键的化合物一定是离子化合物   D．双原子单质分子中的共价健一定是非极性键