1．what do you think of the new ________ (制度)? 2．“what happened？” john's mother asked him in a ________ (温和的) voice. 3．before the earth's protective ________ (大气层) was formed, there was no life except in the sea. 4．with the ________ (引力) of the moon and the sun each day, tides (潮汐) roll in and roll away. 5．he managed to finish the race, ________ (不像) more than half of the competitors.
