Ⅰ.根据首字母或汉语注释，写出单词的正确形式
1．In basketball matches, American players have an obvious ________ (优势) in height.
2．Be careful! A red light is usually a ________ (信号) of danger.
3．New problems ________ (出现) every day.
4．Which ________ (类型) of tea do you prefer?
