A：充分不必要条件
B：必要不充分条件
C：充要条件
D：既不充分也不必要条件
下列合并同类项的结果正确的是 （ ）
长江发源于____ 山脉，全长____ 千米，自西向东注入____ 海。
用恰当的单词填空完成表格。
College students volunteer in the US
In ____
They ____books to the sick people or listen to their problems.
In old people's homes
They help to clean up or go ____.
In the ____clubs
They remember the problems of boys and girls
