题目

A city without cars would be very strange, right? But Venice is such a city. Venice is in the northeast of Italy. It wasn't built on land, like Beijing or Shanghai, but on more than 110 islands. Seawater is everywhere around the city.Even so, travel isn't difficult. The waterways have always been the best way to get around. There are 117 waterways and more than 400 bridges that can guide you where you want to go. People in Venice move from place to place by boat. They like to enjoy the scenery(风光) and cool summer nights while taking boat trips. They can talk to other people as they go alon在下列函数中，当x取正数时，最小值为2的是(　　)A．y＝－x－B．y＝lgx＋C．y＝＋D．y＝x2－2x＋3