题干
----- Sorry, Ann. I’m afraid that I can’t go to the magic show by David Copperfield with me.
----- ________ Who knows when he will be back here again?
----- ________ Who knows when he will be back here again?
A：It doesn’t matter.
B：Do as you like.
C：What a shame.
D：Take it easy.
答案(点此获取答案解析）
C
伸状态。如图所示。现在突然剪断下端的细线。则从剪断细线开始到弹簧恢复原长以前，箱对地面的压力变化情况。下列判断正确的是（ ）
