未知题型 若已包括头文件＜string.h＞且已有定义char s1[18]，s2={'ABCDE'}和int i，现要将字符串 'ABCDE'赋给s1，下列语句错误的是( )。A.strcpy(s1,s2)B.strcpy(s1, 'ABCDE')；C.s1='ABCDE'；D.for(i=0；i＜6；i++) s1[i]=s2[i]；

多项选择题 单相交流电压器带阻感负载时电流谐波的特点是() A. 电流谐波次数只含3、5、7…等次谐波 B. 随着次数的增加,谐波含量减少 C. 阻感负载时的谐波电流含量比电阻负载时少一些 D. α角相同时,随着阻抗角的增大,谐波含量有所减少

未知题型 若以'a+'方式打开一个已存在的文件，则下列叙述正确的是( )。D.以上三种说法都不正确

单项选择题 一种草质藤本植物，具卷须，花单性，雄蕊5枚，子房下位，侧膜胎座，结瓠果，这种植物属于( 　)科。

单项选择题 下列硫化物中既不溶于Na2S，又不溶于Na2S2 的是   （   ）

未知题型 The word 'diurnal' (in Paragraph 3) is closest in meaning to ______.A.day-and-night'sB.everydayC.two days'D.yearly

未知题型 The climate of Earth is changing. Climatologists are confident that over the past century, the global average surface temperature has increased by about half a degree Celsius. This warming is thought to be at least partly the result of human activities, such as the burning of fossil fuels and the clearing of forests for agriculturE.As the global population grows and national economies expand, the global average temperature is expected to continue increasing by an additional 1.0 to 3.5℃ by the year 2100.Climate change is one of the most important environmental issues facing humankinD.Understanding the potential impacts of climate change for natural ecosystems is essential if we are going to manage our environment to minimize the negative consequences of climate change and maximize the opportunities that it may offer. Because natural ecosystems are complex, nonlinear systems, it follows that their responses to climate change are likely to be complex. Climate change may affect natural ecosystems in a variety of ways. In the short term, climate change can alter the mix of plant species in land ecosystems such as grasslands. In the long term, climate change has the potential to dramatically alter the geographic distribution of major vegetation types--savannas, forests, and tundrA.Climate change can also potentially alter global ecosystem processes, including the cycling of carbon, nitrogen, phosphorus, and sulfur. Moreover, changes in these ecosystem processes can affect and be affected by changes in the plant species of the ecosystem and vegetation typE.All of the climate change-induced alterations of natural ecosystems affect the services that these ecosystems provide to humans.The global average surface temperature increase of half a degree Celsius observed over the past century has been in part due to differential changes in daily maximum and minimum temperatures, resulting in a narrowing of the diurnal temperature rangE.Decreases in the diurnal temperature range were first identified in the United States, where large-area trends showed that maximum temperatures have remained constant or increased only slightly, whereas minimum temperature have increased at a faster ratE.In this issue, Alward et al. report on the different sensitivities of rangeland plants to minimum temperatures increases.Which of the following is NOT mentioned as a reason for the global warming?A.The burning of fuels such as coal or oil.B.The clearing of forests.C.The cultivation of farmlanD.D.The negative consequences of human activities.

未知题型 'Feel out of sorts' in the second paragraph could be best replaced by '______'.A.put things in orderB.be in a bad moodC.search for tranquilizersD.need a mood-raiser

单项选择题 在同一台数控机床上，应用相同的加工程序，相同代码加工一批零件所获得的连续结果的一致程度，称为重复定位精度。（    ）A.对B.错

多项选择题 乾隆皇帝的书房名叫“三希堂”，其中“三希”表示的是以下三件书法珍品（ ）。