___ we know, in a chemical change, energy cannot be created, ____

“Could you do me a favour and take the box up to the six floor？” “_______.”

My mother says that we won’t go on a trip to Hong Kong. I just can’t understand.— _______. You were looking forward to it.

teacher, he has never given hisstudents so difficult a problem ____ they can’t work out

We ______ to paint the whole house but finished only the front part that day.[ ]