The Abbey Road pedestrian crossing in Northern London is one of the world's most famous ____ it is on the cover of Beatles album. Now, the British government ____(put) it on the list of national heritage sites.

    ____ (normal), only buildings and other architectural sites get the award. It is the first time ____ a section of street became part of ____ (Britain) National Heritage. The crossing is near the Abbey Road studios ____the Beatles made most of their records. Today it can ____(see) around the world on a special webcam(网络摄像头). The studio building ____(it)became listed by British Heritage last February. The photographer of the picture said he only had 10 minutes ____(take) it. It became one of the most famous album covers of all times. The Abbey Road  album was ____last one the Beatles completed before they broke up.

下列问题中，是正比例函数的是（　　）