题干

假如地轴与黄道面相交成90度,那么,当地球自转和公转时,可能发生的现象是

A:太阳直射点将在南北极点之间来回移动

B:全球任何地方得到的太阳热量均相等

C:全球仍然有昼夜长短变化

D:地球上任何地方都无四季变化

上一题 下一题 0.0难度 选择题 更新时间:2019-09-16 07:39:48

答案(点此获取答案解析)

D

同类题2

阅读理解

    Airbags, now found in almost every vehicle, have saved countless lives and largely reduced the severity of injuries in crashes. Similar technology could greatly reduce broken hips (髋部) resulting from a fall, something most seniors fear.

    Dr. Robert Buckman and his start-up company, Active Protective in Allentown, Pennsylvania, has developed a promising solution, a wearable airbag that can protect hip bones in the event of a fall. The idea was the result of Dr. Buckman's years as a doctor at Temple University. He noticed how many elderly people were being brought into hospitals with broken hip due to falls, and how they often never completely recovered from the injuries. He started to ask what he could do for these people, and that was when he started trying to figure out whether there was a way of helping people who were at the highest risk of falling and suffering these kinds of injuries.

    The device is worn much like a regular belt, but on the outside of the clothing, and it includes sensors that monitor the movement of hips. If the device detects that the person, is falling, an airbag opens before the person hits the ground, cushioning the fall. When the wearer hits the ground, the bag reduces the force to the hip bones by 90 percent, enough to avoid the majority of hip injuries.

    With one out of every three people aged 65 and older suffering serious falls each year, Active Protective has a big market for its wearable device. It also has the potential to sizably reduce hip - related health care expenses: Hip injuries among the elderly cost the US health care system in 2012 $30 billion, which doesn't include the long-term care expenses associated with the high percentage of patients that can no longer live independently.