What do you know about the sea? Some people know about it, but others don’t. The sea looks beautiful on a fine sunny day, the sea is very big. In the world, there is more sea than land. Do you know Hainan Island? It’s really very nice. We can see beaches, trees and the sea. We can swim and visit a lot of beautiful places.

从北京到天津的公路全长是____千米？

一辆汽车每小时行50千米，下午1∶00从北京出发，4∶00以前能到天津吗？____

质量相等的一个空心铅球和一个木块均漂浮在水面上，空心铅球排开水的体积____（选填“大于”、“小于”或“等于”）木块排开水的体积．