单词拼写（每小题1分，满分5分）
根据首字母及汉语提示，完成下列单词的拼写，使句意明确，语言通顺。
It is __________( 危险的 )to swim in the river.
If you want to know more          (信息) ,you can call me.
Keep quiet! I can’t hear what the teacher said ________(清楚地).
There are two________( 百）people planting trees on the hill.
It is difficult to ________(选择）between the two books.