题目

设是可导函数，且，则=（ ）  A．        B．         C． 0      D． 答案：D 解析：若与相交,则内没有直线与,故A错误;若,则内没有直线与相交,故B错误;若,则内没有直线与异面,故C错误;故选D。 点评:直线与直线之间的位置关系有三种:平行、异面和相交。解决本题可用到排除法。Asia has many wild places. The following national parks are among the most famous in Asia. People come to visit them from near and far in order to appreciate the unique qualities of the land and everything on it. Have you ever visited any of these Asian national parks?Jiuzhai Valley National Park, ChinaThe extraordinarily beautiful park is famous for its fascinating blue-green lakes, waterfalls and its unique wildlife. Located in the Minshan Mountain, Sichuan Province, it is a breathtaking park because of its scenery and it is also home to nine Tibetan villages, over 220 bird species as well as a number of endangered animals and plants, such as giant pandas, Sichuan golden monkeys and numerous orchids. This park was also declared a UNESCO World Heritage Site in 1992.Khao Sok(考索)National Park, ThailandThis extraordinary park is several miles away from Phuket(普吉岛), yet its remoteness(遥远)prevents it from being visited. Even so, it is well worth a visit as scientists have noted that is rainforest stretches are not only longer than those of the Amazon, but also more divers(多样化的). Animals like tigers, Asian elephants, and macaaues make their home here. Everyone who visits the park, however, seems to want to have a look at the amazing Rafflesia, one of the strangest flowering plants on earth; it smells like smelly meat when it blooms.Nikko(日高)National Park, JapanIt is lovely to visit this park all the year round with its waterfalls and picturesque Lake Chuzenji. And it is especially worth visiting in autumn when the leaves change from green to deep red and orange. Set with UNESCO protected shrines(神坛)and temples, the park is a unique mixture of natural and man-made attractions. With various routes perfect for adventurous hikers, a visit to the Nikko National Park is not to be missed.If you want to know more information about Asian famous national parks, you can log in http://www.travel.Amerikanki.com. If you want to enjoy all the above, welcome to call 050-24689120, and we can give a reasonable price.【1】What does the underlined word “orchids” probably refer to?A. Wild animals. B. Endangered flowers.C. Rare monkeys. D. Tibetan buildings.【2】Compared with Amazon, Khao Sok National Park has______.A. stranger flower plantsB. More animalsC. more varieties of rainforestsD. more visitors【3】If you’re an adventurous hiker, which park would you probably choose to visit?A. Jiuzhai Valley National park.B. Khao Sok National Park.C. Nikko National Park.D. Zhangjiajie National Park.