一个沿轴作简谐振动的小球，振幅为 ，速度的最大值为 。若取速度具有正的最大值时 。试求：
（1）振动频率；
（2）加速度的最大值；
（3）振动的表达式。

如图是一个几何体的三视图，根据图示的数据可计算出该几何体的表面积为__________.

按玻尔的氢原子理论，电子在以质子为中心、半径为的圆形轨道上运动，如果把这样一个原子放在均匀的外磁场中，使电子轨道平面与垂直，如图所示，则在不变的情况下，电子轨道运动的角速度将（  ）

执行右边的程序框图，若输入的值为，则输出的的值为__________．

　　Our risk of cancer rises dramatically as we age. So it makes sense that the elderly should be routinely screened for new tumors — or doesn’t it?
　　While such vigilant (警觉的) tracking of cancer is a good thing in general, researchers are increasingly questioning whether all of this testing is necessary for the elderly. With the percentage of people over age 65 expected to nearly double by 2050, it’s important to weigh the health benefits of screening against the risks and costs of routine testing.
　　In many cases, screening can lead to surgeries to remove cancer, while the cancers themselves may be slow-growing and may not pose serious health problems in patients’ remaining years. But the message that everyone must screen for cancer has become so deep-rooted that when health care experts recommended that women under 50 and over 74 stop screening for breast cancer, it caused a riotous reaction among doctors, patients and advocacy groups.
　　It’s hard to uproot deeply held beliefs about cancer screening with scientific data. Certainly, there are people over age 75 who have had cancers detected by routine screening, and gained several extra years of life because of treatment. And clearly, people over age 75 who have other risk factors for cancer, such as a family history or prior personal experience with the disease, should continue to get screened regularly. But for the remainder, the risk of cancer, while increased at the end of life, must be balanced with other factors like remaining life expectancy (预期寿命).
　　A recent study suggests that doctors start to make more objective decisions about who will truly benefit from screening- especially considering the explosion of the elderly that will soon swell our population.
　　It’s not an easy calculation to make, but one that makes sense for all patients. Dr. Otis Brawley said, “Many doctors are ordering screening tests purely to cover themselves. We need to think about the rational use of health care.”
　　That means making some difficult decisions with elderly patients, and going against the misguided belief that when it comes to health care, more is always better.