In a sports team each player has a clear role，and there are few occasions_____ members are confusedor uncertain of their roles

In front of the famous big trees ________ a family, ________ the parents treat their child like a friend.

As we all know, __________ of the earth surface is covered by water.

When ______ help, one often says “Thank you.” or “It’s kind of you.”

I forget to bring a pen．Wouldyou lend me ____ A．one