题干

为了判断一根铁棒是否具有磁性,小明进行如下四个实验,根据实验现象不能确定该铁棒具有磁性的是(     )

A:将悬挂的铁棒多次旋转,静止时总是南北指向

B:将铁棒一端靠近小磁针,相互吸引

C:将铁棒一端靠近大头针,大头针被吸引

D:水平向右移动铁棒,弹簧测力计示数有变化

上一题 下一题 0.0难度 选择题 更新时间:2019-09-08 08:18:56

答案(点此获取答案解析)

B

同类题3

阅读下列短文,从每小题所给的A、B、C、D四个选项中选出一个最佳选项。

    Sarasota, Florida teen band The Garbage-Men is performing on the stage. The band has five members. They are Jack Berry, Ollie Gray, Harrison Paparatto, Austin Siegel and Evan Tucker. The five teens are making music from waste. The Garbage-Men band's instruments are made from recycled things. The guitars are boxes. A horn(号) is made from pipes. The keyboard is formed from old bottles.

    The band started about two years ago. Jack Berry who was in eighth grade at the time decided to make a playable, home-made guitar, after some trial-and-error(反复试验), he ended up building it from a cereal box, a yardstick and toothpicks. After Jack showed his creation to his friend Ollie Gray, Ollie had the idea to form a band using other home-made instruments as a way to improve recycling. “We want to show people there is more to recycling than throwing things away in the bin.” Jack, 16, told TFK. “You can actually reuse materials.”

    The Garbage-Men plays at local events around Sarasota, including festivals, farmer's markets and community fundraisers. Typically, the teens will set up on the street and perform popular songs from the 1960s, including classic Beatles tunes and crowd favorite “Wipe Out,” by The Surfaris. In between sets, they talk about recycling and offer tips for how to help the environment. While they perform, Jack's little brother Trent, 11, gives out flyers(宣传单) about recycling and helps sell the band's CDs and other musical products.

    The band donates(捐赠) the money from sales to charity. They have raised more than $2,500 for Heifer International. The organization gives farm animals, seeds and agricultural(农业的) training to people in poor countries to help end poverty and hunger. “It's a good, sustainable-development (持续发展的)charity,” Jack says, “By donating one animal, you help the whole community.”

    The band, all tenth graders, tries to play a show every week. They've also played on a Tampa, Florida radio station and auditioned(试演) for America's Got Talent. The teens hope to eventually take their shows on the road by touring in other states. “Music is a really good way to get a good message across to people because it's really accessible(可接近的),” Jack says. Their instruments may be rubbish, but their message isn't.