制约新疆农业生产的主要因素是 （   ）

已知△ABC∽△DEF，且相似比为2：3，则△ABC与△DEF的对应高之比为（　　）

阅读下面的文字，完成下列小题。

                                                                                    清晨我漫步在山坡谷地，

                                                                                    晨光宣泄着永恒的秘密，

                                                                                    山涧里流倘出一条小溪，

                                                                                    她在歌、在唤、在吐露心曲：

                                                                                    生活并非安逸，

                                                                                    它是思念和希冀。

                                                                                    死亡并非哀歌，

                                                                                    它是失望与憔悴。

                                                                                    智者不在言词，

                                                                                    其秘密在言词背后藏nì。

                                                                                    伟人不在高位，

                                                                                    不屑权位者才配享荣誉。

                                                                                   （纪伯伦《小溪，你说什么》节选）

请写一个图象在第二、四象限的反比例函数解析式：____ ．