根据所给的英文释义写出下列单词
问题描述：
根据所给的英文释义写出下列单词
1.( ) a circular object connected at the center to a bar,which is used for making vehicles or parts of machines move
2.( ) either of two children born to the same mother on the same occasion
3.( ) a large area of water surrounded by land and not connected to the sea
4.( ) thing that needs attention and needs to be solved
5.( ) the body temperature is higher than usual and the heart beats very fast
答
2.twin
3.lake
4.issue
5.fever