①接触面所受的压力大小；

②接触面的粗糙程度；

③接触面积的大小．

通过如图所示实验操作验证这些猜想：

    Nowadays, the life of many people in the world is____(affect) by globle warming. For example, greenhouse gas has a bad effect____both people and environment. The earth's surface temperature____(go) up by about 1 degrees centigrade in the past100 years. As a matter of fact, we may feel that we can hardly put up with the extremely hot summer and we can't get accustomed to warm winter. The rise of the earth's surface temperature has made much ____(different) to human health, the existence of creatures ____ the balance of ecosystems. There is no doubt that it is human activities that result____the bad environment. As a ____(consequent), conditions permitting, all countries in the world should try their best ____(improve) our environment. Even if our effect is limited, it will____(eventual) make a great difference if we keep on____(work) together to deal with global warming. Without all people's joint efforts, what would our future be like?