题目

已知M＝4x3+3x2﹣5x+8a+1，N＝2x2+ax﹣6，若多项式M+N不含一次项，则多项式M+N的常数项是（ ） A．35              B．40               C．45              D．50 答案：A． 9阅读理解。The Cuban iguana is a species of lizard（蜥蜴） of the iguana family. It is the largest of the West Indian rock iguanas, one of the most endangered groups of lizards. This species with red eyes and a thick tail is one of the largest lizards in the Caribbean.The Cuban iguana is primarily herbivorous; 95% of its diet consists of the leaves, flowers and fruits from as many as 30 plant species, including the seaside rock bush and various grasses. However, Cuban iguanas occasionally consume animal matter, and individuals have been observed eating the dead flesh of birds, fish and crabs. The researchers wrote that quite a few people on Isla Magueyes could have caused this incident.The Cuban iguana is distributed throughout the rocky southern coastal areas of mainland Cuba and its surrounding islands with a wild population booming on Isla Magueyes, Puerto Rico. It is also found on the Cayman Islands of Little Cayman and Cayman Brac, where a separate subspecies occurs. Females guard their nest sites and often nest in sites half destroyed by Cuban crocodiles. To avoid the attack from them, the Cuban iguana often makes its home within or near prickly-pear cacti（仙人掌）.In general the species is in decline, more quickly on the mainland than on the outlying islands. One of the reasons for their decline is habitat destruction caused by the over consuming of farm animals, housing development, and the building of tourist resorts on the beaches where the animals prefer to build their nests. Although the wild population is in decline, the numbers of iguanas have been sharply increased as a result of captive-breeding（圈养）and other conservation programs.【题文1】The underlined word "herbivorous" （Paragraph 2） probably means .A. dangerous B. gentleC. plant-eating D. flesh-eating1.Why does the Cuban iguana build its nest near prickly-pear cacti?A. To keep itself cool. B. To get the food easily.C. To stay away from people. D. To avoid crocodiles' attack.2.How many reasons are mentioned for the habitat destruction?A. Two. B. Three.C. Four. D. Five.3.What's the author's purpose of writing the text?A. To give us a brief introduction to the Cuban iguana.B. To show he is concerned about the Cuban iguana.C. To explain reasons for the Cuban iguana's decline.D. To draw people's attention to the endangered Cuban iguana.