根据句意和汉语提示，写出单词的正确形式。
小题1:On Children’s Day, children could not hide their______________(excite).
小题2:He comes from the _______________(south) city of China.
小题3:Jim is happy to live on the ____________ (twelve) floor because he enjoys the view out of the windows.
小题4:Mr. and Mrs. Wang will celebrate their fifteen years of ____________ (marry) this weekend．
小题5:The water in the river is______________(harm). You can drink it without cooking.
小题1:excitement
小题2:southern
小题3:twelfth
小题4:marriage
小题5:harmless
小题1:考查名词的用法。形容词性物主代词their后跟名词。故填excitement。
小题2:考查词性转换。southern“南部的，南方的”。在此修饰名词city。故填southern。
小题3:考查序数词。twelve的序数词形式是twelfth。第十二层是the twelfth floor。故填twelfth。
小题4:考查词性转换。marry“结婚”，名词形式是marriage。故填marriage。
小题5:考查形容词的用法。Is是系动词，后跟形容词作表语。根据句意可知，应填“无害的”。故填harmless。