C

    There are many new ways of shopping in the world. Do you know all of them?

    One popular way is catalog shopping(目录购物). There are catalogs for almost anything you need—like clothes, furniture, cooking and so on. People also order about 40% of their music from music club catalogs.

    Another way of shopping is shopping by TV. It began in 1986. About 5% to 8% of the Americans now shop by television. People say that it is easier than shopping in a shop. TV shopping is late at night, so people can "go shopping" happily after a day's work.

    Computer shopping or "shopping online" is interesting to more and more people. Is computer shopping the way of tomorrow? Already, people can use their computers to order many different things, such as computers, flowers, food and T-shirts. Soon people may be able to shop for anything, anytime and anywhere in the world.

为了探究音调与什么因素有关，小明设计了下面几个实验，如图所示，你认为不能够完成探究目的是（   ）

一只标有“12V  6W”字样的电灯，当它正常工作时，通过灯丝的电流为____ A，灯丝电阻为____ Ω；若把它接在电压为15V的电路中，应给它____ 联一个阻值为____ Ω的电阻，电灯才能正常发光．