You            arrive at 6:00 am, but you arrived at 7:00 am last Sunday. Don't be late this time. [ ]

A. supposed to

B. were supposed to

C. are supposed to

D. should be supposed to

下列现象中，利用内能做功的是（　　）

A．冬天在户外时两手相互搓一会儿就暖和了

B．刀在砂轮的高速摩擦之下溅出火花

C．火箭在“熊熊烈火”的喷射中冲天而起

D．盛夏在烈日之下的柏油路面被晒熔化了