Could you help me do some cleaning after school— If I _______, I will do it.

An underwater hotel has opened in Africa，with its rooms＿on the bottom of a three－level floating building．

It was at 12 o’clock _________ they came home fromschool

It was careless ___ you to have left your clothes outside all night.— My God! _____

er having finished mopping thefloor, he puts the mop back ______ it belonged