题目

A dog-lover has invented a high-tech way of feeding his pet by Twitter（推特，流行社交网络）. Computer expert Nat Morris, 30, has designed a system to give his pet a “tweet treat” by sending him a Twitter message. His dog Toby gets some delicious dog biscuits from a computer-controlled food machine whenever Nat sends a message to “@feedtoby”. Nat often works away from home and isn’t always able to feed Toby by hand. But his new invention allows Nat to feed his dog from anywhere in the world. Nat said, “Toby absolutely loves it. At first he didn’t know what was 周末，在江滨公园可以见到骑双人自行车的游客，如图所示．在骑行过程中以    为参照物，骑车人是运动的；以自行车为参照物，骑车人是    ．