题目

某同学家新房装修时，在地面与窗台间放置一斜木板，将瓷砖沿木板从地面匀速拉上窗台．如图所示，已知窗台高3m，木板长5m，瓷砖重500N，沿斜面所用拉力400N，则此过程中所做的有用功为 J，斜面的机械效率是，瓷砖与木板间的摩擦力为 N． 答案：【1】1500【2】75%【3】100先通读下面的短文，然后根据短文内容和所给首字母，在空格内填入一个适当的词，使短文意思完整。所填单词必须在答题卡标有题号的横线上完整写出。Japan is e________ 【小题1】its worst crisis（危机）since World War II. A terrible earthquake a________ 【小题2】 northeast Japan on March 11th. It was measured at magnitude 9.0. This is the s________ 【小题3】earthquake in Japan’s recorded history.The earthquake was f________ 【小题4】by a tsunami. Its wave was up to 10 meters high and s________ 【小题5】away everything in its path, including houses, cars, buildings and trees. The number of death r________ 【小题6】 6,405 last Friday morning, with 10,259 missing. The number will likely go b________ 【小题7】10,000 in one state （县）alone. Survivors along northeastern coast were in great n________ 【小题8】of drinking water, electricity and proper food. Compared with the earthquake, the nuclear leak（核泄漏）had a w________【小题9】effect on the people in Japan. An explosion（爆炸）had hit a building at the Fukushima Daiichi Nuclear Station and smoke r________【小题10】from the building last Friday. People were told to stay indoors if they lived w________ 【小题11】18 miles away from it. People were worried if the radioactive material would be blown over the area because of the wind d________【小题12】. According to the WHO, the radiation risk had no sign of threatening（威胁）anywhere else in Asia at present. March 22nd , 2011