实验室测量物质的密度：

（1）使用托盘天平之前，应将天平放在什么上，再将游码置于标尺左端的零刻线处。若发现指针指在分度盘中央的右侧，这时应将横梁右端的平衡螺母向哪边旋动？

（2）图1中游码所对的刻度值是多少g？

（3）测一块岩石的密度（如图2甲、乙所示），将实验测量的数据填入表格，并计算出岩石的密度。

A：Jane，I called you just now, but you didn't pick up．____?

B：I was reading a story called the fox and the crow(《狐狸和乌鸦》)．

A：____?

B：Oh ,it's very educational．

A：____?

B：Of course．One day, the crow got a piece of meat．The fox was very hungry and wanted to eat the meat．Then the fox said hello to the crow．But the crow didn't answer．

A：____ ?

B：Then the fox said the crow had a beautiful voice and asked the crow to sing a song．The crow was very proud(得意的)and wanted to sing．When it opened its mouth，the meat dropped and the fox got it．

A：The crow was really silly．

B：____．The fox wasn't telling the truth．The crow had a terrible singing voice．