题干
根据下列句子及所给单词的首字母，在答题卷上按题号写出各单词的完全形式（每空限填一词）。
⑴My grandfather likes to water the f____ in the garden on weekends.
⑵The boy is too young. So don't leave him a____ at home.
⑶If I don't help my mom do some h____ on weekends, my mother will be very angry with me.
⑷Last night I didn't go to bed u____ the TV program was over.
⑸Last Sunday I w____ a letter to my father.
⑹I need to look smart for my job i____ .
⑺He f____ his test last week. He should study hard.
⑻He m____ his teacher in the street yesterday.
⑼When the little girl saw the big tiger, she felt very s____ .
⑽Last week, I p____ 500 yuan for my new bike.
答案(点此获取答案解析）
flowers,alone,housework,until,wrote,interview,failed,met,scared,paid
．它在电路中的作用是：当电流从“+”极端流入时，二极管对电流的阻碍作用很小，此时二极管可视为一段导线；当电流从“﹣”极端流入时，电流几乎不能通过它，即电流几乎为零，此时二极管可视为绝缘体．小明通过实验探究，验证了它的性能．请你根据二极管的性能解决相关问题．（假设实验过程中二极管都完好无损）