Once Einstein was waiting for one of his friends.While he wa

Once Einstein was waiting for one of his friends.While he was waiting,he became in deep _.
It began to rain.The rain kept on for some time.When he ____ out a piece of paper form hia pocket to write something down,the paper was ____ and then he knew that it was raining.His clothes had become wet from the rain.But after he put the paper into his pocket,he ____ he was standing in the rain again.This is because they are too ____ in their studies.｛ 短文填空,一空一词｝