1.i think the microwave oven is the (two) most helpful inven

helpful,I,is,think,most,the,telephone,the,invention(连词成句） ---I think the Internet is very helpful. I think the most helpful invention is light bulb. It  & when do you think ——? A,was the microwave oven invented B th 英语翻译If the pie is h____ in the microwave oven,it will be mor 14.While _____ the food with the microwave oven,I heard some I think it helpful to do the housework和I think it is helpful john put his wallet into the microwave oven _______ . John put his wallet into the microwave oven ___. i think the plan for writing is helpful I think the Internetr is very helpful怎么回答? What do you think is the most helpful invention,do you think