下载APP
举一反三
【单选题】qz149: 某加速器将电子加速到能量E = 2×106 eV时,该电子的动能EK =( )eV。(电子的静止质量me = 9.11×10-31 kg, 1 eV =1.60×10-19 J)
A.
2.49×106
B.
1.49×106
C.
1.67×106
D.
2.67×106
【单选题】设备是在各种不同的环境条件下运转的，承受着各种（ ）与能量的作用，这些作用会使设备的技术状态发生变化，设备的性能劣化，最终导致设备发生故障。
A.
应力
B.
力量
C.
能量
D.
压力
【单选题】Every year more than half a million American kids have drainage(排泄) tubes surgically implanted in their ears to combat persistent infections. The procedure, known as tympanostomy, may not be as (62) a...
A.
[A] feeling [C] health
B.
[B] hearing [D] memory
【单选题】Section BDirections: There are 2 passages in this section．Each passage is followed by some questions or unfinished statements．For each of them there are four choices marked A, B, C and D．You should de...
A.
could not easily be absorbed by the human body
B.
were potentially harmful to people's health
C.
were too expensive for daily consumption
D.
could not provide any cure for vitamin deficiencies